Even with session explicitly enabled <%@page session="true"%>, session does not persist. The same exact code works fine on JRun and WebSphere.
This is caused by bug in ICE Browser (Cookies are evidently not enabled so
session #s can't be passed).
Use external browser instead. Set Tools->JSP->Web Browser and
*** This issue has been marked as a duplicate of 10432 ***
Resolved for 3.4.x or earlier, no new info since then -> closing.