Error rendering portlet en OC4j 10.1.2

[Carlos Nicolas]

Hi
I 've two diferent versions of OC4j (10.1.2 and 10.1.3) and I try to deploy a same ear, in the 99% of application i haven't any problems, but in a specific long action (the app is made with strust) i've this log error

Error occurred while rendering portlet - see provider log file for details

In both cases i'm using the same machine, the same jdk and of course the same database (oracle 9)

The error only appears in oc4j 10.1.2 and not in oc4j 10.1.3, but we need to solve this because some servers were the app is deployed are using this version of OC4j

Thans in advance.
If you need some more detailsplease say me