Tapestry render variable in zone is null

Hi there,

I'am new to that list and want to say hello to every one here.

Problem description: I'am working with a tapestry form containing a loop
iterating over a bean collection. Inside the loop component a zone
component is nested. The client side zone id is calculated from a hard
coded prefix and suffix taken from one of the render variables properties,
lets say the id.

Page rendering works fine if page is called via noral http request. Zone
update is triggered by an onValueChange event fired by a select component
contained inside the zone. And now things get weird. The render variable
used to build the zones client id seems to be null after the ajax request.

Coding it without a form around the loop and replacing the select by an
event or action link works fine.

Currently I have no further idea. Any help is appreciated.

Regards
Erich