Application Server Session timed out (-11) (lack of debug in internal ITS)

Question

Dear Sirs,
I get the error message below, when I try to run a IAC through internal ITS. The IAC worked for a while (<30 minutes), and then suddenly this error appeared.
I can see that this error message has been asked about previously, but then in connection with statefull/stateless BSP applications (e.g "Session timed out thread", on this forum May 31 2005).
In this thread the solution is apparently to alter the 'rdisp/plugin_auto_logout', is this the case for us as well?
I have read Error handling using the ICM , but not able to actually beeing able to pinpoint the problme.
All our other IAC are working it is only a problem with one of them. The problem is still valid even if I log on with different user, and the error is still there now even after two hours. The problem transaction is a altered version of the WSTA, and I am able to get the first screen where I enter the store number. 
Any tips or suggestions to pinpoint the error?
+400 Session timed out - please log in again
Application Server Session timed out (-11)
Error:     -11
Version:     6040
Component:     ICM
Date/Time:     Thu Apr 27 14:13:56 2006
Module:     icxxthr_mt.c
Line:     1719
Server:     xxXXXt_TXX_XX
Detail:     Session does not exist+
In SM21 :
+Transaction Canceled ITS_P 025 ( 0x2103: Interpreter: The input contains errors. )                                                              
Documentation for system log message D01 :
The transaction has been terminated.  This may be caused by a termination message from the application (MESSAGE Axxx) or by an error detected by the SAP System due to which it makes no sense to proceed with the transaction.  The actual reason for the termination is indicated by the T200 message and the parameters.                         
Additional documentation for message ITS_P               025 Template interpretation terminated - internal error &1                        
No documentation exists for message IT025+                                     
Best regards,
Jørgen

Answer 1

Dear Sirs,
The error has been solved. It was a matter of an illegal input sendt to the RetailHeaderFunction.
However, this makes way for another question.
On the standalone ITS, it was possible to get error messages which indicated where the code contained errors, when it was runned.
How is it possible to make the internal ITS gives better feedback (errors?), and show where the error is?
Jørgen