When I click the preview viewer button on javafx editor, couldn't see any of the TextField components included in the
.fx file.

A portion of the message Log is below:

uncaught FX exception: 'Component was null for Widget javafx.ui.TextField {row: javafx.ui.Row {alignment:
javafx.ui.Alignment {name: \'BASELINE\' id: 3} resizable: false} column: javafx.ui.Column {alignment:
javafx.ui.Alignment {name: \'LEADING\' id: 1} resizable: true} inBoundsListener: false focusListener: new FocusListener
{}@15901789 null keyboardAction: [] component: null focusable: true focused: false onMouseEntered: null onMouseExited:
null onMousePressed: null onMouseReleased: null onMouseClicked: null onMouseMoved: null onMouseDragged: null
onMouseWheelMoved: null onKeyUp: null onKeyDown: null onKeyTyped: null propertyChangeListener: null textField: null
verifier: null value: \'Joe\' text: \'\' columns: 25 editable: false enableDND: false horizontalAlignment: null
selectOnFocus: false selectionStart: 0 selectionEnd: 0 inSelectionUpdate: false}'
	at throw "Component was null for Widget {w}";
("jar:file:/home/leonux/Tools/IDE/netbeans/6.0m10/nb6.0/modules/ext/javafx/javafxrt.jar!/javafx/ui/GroupLayout.fx", Line
116)
	at this.addColumns(panel, layout, hgroup)
("jar:file:/home/leonux/Tools/IDE/netbeans/6.0m10/nb6.0/modules/ext/javafx/javafxrt.jar!/javafx/ui/GroupPanel.fx", Line 49)
	at frame.setContentPane(w.getComponent())
("jar:file:/home/leonux/Tools/IDE/netbeans/6.0m10/nb6.0/modules/ext/javafx/javafxrt.jar!/javafx/ui/Frame.fx", Line 303)
	at this.setContentPane(value)
("jar:file:/home/leonux/Tools/IDE/netbeans/6.0m10/nb6.0/modules/ext/javafx/javafxrt.jar!/javafx/ui/Frame.fx", Line 298)
	at new Frame {content: new GroupPanel {var: firstNameRownew Row {alignment: BASELINE}, var: lastNameRownew Row
{alignment: BASELINE}, var: labelsColumnnew Column {alignment: TRAILING}, var: fieldsColumnnew Column {alignment:
LEADING, resizable: true}, rows: [firstNameRow, lastNameRow], columns: [labelsColumn, fieldsColumn], content: [new
SimpleLabel {row: firstNameRow, column: labelsColumn, text: "First Name:"}, new TextField {row: firstNameRow, column:
fieldsColumn, columns: 25, value: bind model.firstName}, new SimpleLabel {row: lastNameRow, column: labelsColumn, text:
"Last Name:"}, new TextField {row: lastNameRow, column: fieldsColumn, columns: 25, value: bind model.lastName}]},
visible: true} ("javafx.netbeans", Line 17)
	at unit.execute() ("javafx.netbeans.preview", Line 70)
	at operation <<javafx.ui.GroupLayout>>.addColumns(this: GroupLayout, host: <<java.awt.Container>>, layout:
<<org.jdesktop.layout.GroupLayout>>, hgroup: <<org.jdesktop.layout.GroupLayout$SequentialGroup>>) {
    if (columns == null and content.column == null) {
        columns = new Column {};
        for (i in content) {
            i.column = columns[0];
        }
    }
    for (i in columns) {
        var [pgroup = layout.createParallelGroup(i.alignment.id, i.resizable)];
        hgroup.add(pgroup);
        var [comps : <<java.awt.Component>> = []];
        for (j in content where j.column == i) {
            if (j instanceof <<javafx.ui.Widget>>) {
                var [w = (Widget)j];
                var [c = w.getComponent()];
                if (c == null) {
                    throw "Component was null for Widget {w}";
                }
                if (w.sizeToFitColumn) {
                    insert c into comps;
                }
                if (j.horizontal <> null) {
                    var [spring = j.horizontal];
                    pgroup.add(c, spring.min, spring.pref, spring.max);
                } else {
                    if (i.resizable) {
                        pgroup.add(c, 0, <<org.jdesktop.layout.GroupLayout>>.PREFERRED_SIZE, MAX_INT:Number);
                    } else {
                        pgroup.add(c, <<org.jdesktop.layout.GroupLayout>>.PREFERRED_SIZE,
<<org.jdesktop.layout.GroupLayout>>.PREFERRED_SIZE, <<org.jdesktop.layout.GroupLayout>>.PREFERRED_SIZE);
                    }
                }
            } else {
                if (j instanceof <<javafx.ui.Gap>>) {
                    var [spring = j.horizontal];
                    pgroup.add(spring.min, spring.pref, spring.max);
                } else {
                    if (j instanceof <<javafx.ui.GroupLayout>>) {
                        var [g = (GroupLayout)j];
                        var [sg = layout.createSequentialGroup()];
                        g.addColumns(host, layout, sg);
                        pgroup.add(i.alignment.id, sg);
                    }
                }
            }
        }
        if (sizeof comps > 0) {
            layout.linkSize(comps, layout.HORIZONTAL);
        }
    }
} ("jar:file:/home/leonux/Tools/IDE/netbeans/6.0m10/nb6.0/modules/ext/javafx/javafxrt.jar!/javafx/ui/GroupLayout.fx",
Line 100)
	at operation <<javafx.ui.GroupPanel>>.createComponent(this: GroupPanel): <<javax.swing.JComponent>> {
    panel = new <<javax.swing.JPanel>>;
    panel.setOpaque(false);
    layout = new <<org.jdesktop.layout.GroupLayout>>(panel);
    panel.setLayout(layout);
    layout.setAutocreateGaps(autoCreateGaps);
    layout.setAutocreateContainerGaps(autoCreateContainerGaps);
    var [hgroup = layout.createSequentialGroup()];
    var [vgroup = layout.createSequentialGroup()];
    this.addColumns(panel, layout, hgroup);
    this.addRows(panel, layout, vgroup);
    layout.setHorizontalGroup(hgroup);
    layout.setVerticalGroup(vgroup);
    return panel;
} ("jar:file:/home/leonux/Tools/IDE/netbeans/6.0m10/nb6.0/modules/ext/javafx/javafxrt.jar!/javafx/ui/GroupPanel.fx",
Line 39)
	at operation <<javafx.ui.Widget>>.getComponent(this: Widget): <<javax.swing.JComponent>> {
    if (component == null) {
        var [comp = this.createComponent()];
        var [c = comp];
        if (c instanceof <<javax.swing.JScrollPane>>) {
            c = (<<javax.swing.JComponent>>)(<<javax.swing.JScrollPane>>)c.getViewport().getView();
        }
        if (doubleBuffered <> null) {
            c.setDoubleBuffered(doubleBuffered);
        }
        if (cursor <> null) {
            c.setCursor(cursor.getCursor());
        }
        if (toolTipText <> null) {
            c.setToolTipText(toolTipText);
        }
        if (visible <> null) {
            c.setVisible(visible);
        }
        if (opaque <> null) {
            c.setOpaque(opaque);
        }
        if (background <> null) {
            c.setBackground(background.getColor());
            c.setOpaque(true);
        }
        if (foreground <> null) {
            c.setForeground(foreground.getColor());
        }
        if (awtFont <> null) {
            c.setFont(awtFont);
        }
        if (focusable <> c.isFocusable()) {
            c.setFocusable(focusable);
        }
        var [self = this];
        focusListener = new FocusListener {};
        c.addFocusListener(focusListener);
        if (componentOrientation <> null) {
            c.setComponentOrientation(componentOrientation);
        }
        if (border <> null) {
            try {
                c.setBorder(border.getBorder());
            } catch (e) {
            }
        }
        if (enabled <> null) {
            c.setEnabled(enabled);
        }
        if (size <> null) {
            c.setSize(size);
        }
        if (alignmentX <> null) {
            c.setAlignmentX(alignmentX);
        }
        if (preferredSize <> null) {
            var [dim = c.getPreferredSize()];
            if (dim <> null) {
                if (preferredSize.height <= 0) {
                    preferredSize.height = dim.height;
                }
                if (preferredSize.width <= 0) {
                    preferredSize.width = dim.width;
                }
            }
            c.setPreferredSize(preferredSize);
        }
        if (alignmentY <> null) {
            c.setAlignmentY(alignmentY);
        }
        if (keyboardAction <> null) {
            var [inputMap = c.getInputMap()];
            var [actionMap = c.getActionMap()];
            for (i in keyboardAction) {
                var [k = i.keyStroke];
                var [a = i.action];
                var [j = JKeyStroke.getKeyStroke(k.id, 0)];
                inputMap.put(j, i);
                actionMap.put(i, new Action {});
            }
        }
        if (focusTraversalKeysEnabled <> null) {
            c.setFocusTraversalKeysEnabled(focusTraversalKeysEnabled);
        }
        if (keyListener <> null) {
            c.addKeyListener(keyListener);
        }
        if (mouseListener <> null) {
            c.addMouseListener(mouseListener);
        }
        if (mouseMotionListener <> null) {
            c.addMouseMotionListener(mouseMotionListener);
        }
        if (mouseWheelListener <> null) {
            c.addMouseWheelListener(mouseWheelListener);
        }
        if (x <> null or y <> null or height <> null or width <> null) {
            var [bounds = comp.getBounds()];
            if (x <> null) {
                bounds.x = x;
            }
            if (y <> null) {
                bounds.y = y;
            }
            if (width <> null) {
                bounds.width = width;
            }
            if (height <> null) {
                bounds.height = height;
            }
            if (bounds.width == 0) {
                bounds.width = comp.getPreferredSize().width;
            }
            if (bounds.height == 0) {
                bounds.height = comp.getPreferredSize().height;
            }
            println("setting bounds to {bounds}");
            comp.setBounds(bounds);
        }
        self.inBoundsListener = true;
        x = comp.getX();
        y = comp.getY();
        width = comp.getWidth();
        height = comp.getHeight();
        self.inBoundsListener = false;
        comp.addComponentListener(new ComponentListener {});
        if (focused) {
            do later {
                requestFocus();
            }
        }
        component = comp;
    }
    return component;
} ("jar:file:/home/leonux/Tools/IDE/netbeans/6.0m10/nb6.0/modules/ext/javafx/javafxrt.jar!/javafx/ui/Widget.fx", Line 376)
	at operation <<javafx.ui.Frame>>.setContentPane(this: Frame, w: Widget) {
    if (w <> null) {
        frame.setContentPane(w.getComponent());
        frame.validate();
    }
} ("jar:file:/home/leonux/Tools/IDE/netbeans/6.0m10/nb6.0/modules/ext/javafx/javafxrt.jar!/javafx/ui/Frame.fx", Line 301)
	at trigger on (Frame.content = value) {
    this.setContentPane(value);
} ("jar:file:/home/leonux/Tools/IDE/netbeans/6.0m10/nb6.0/modules/ext/javafx/javafxrt.jar!/javafx/ui/Frame.fx", Line 297)
	at new Canvas {content: bind compileContent()} ("javafx.netbeans.preview", Line 35)
	at __composite__ = this.composeWidget()
("jar:file:/home/leonux/Tools/IDE/netbeans/6.0m10/nb6.0/modules/ext/javafx/javafxrt.jar!/javafx/ui/CompositeWidget.fx",
Line 22)
	at doc.renderPreview(new FXWidget {document: doc}.getComponent()) ("javafx.netbeans.preview", Line 106)