RRMS_MESSAGE_HANDLING not displayed in portal 7.31

Hi Experts,

I'm facing the following problem:
In BW NW 7.0 I defined some messages for customer-exit variables (in INCLUDE ZXRSRU01).
These messages were generated with RRMS_MESSAGE_HANDLING and displayed in variable-screen in portal.
In a new NW 7.31 (Level: 0004) these messages were not displayed in the variable-screen any more.

The "normal" input-checking from SAP (e.g. wrong dateformat, etc) will throw and display an error.
But I'm not able to "raised" a message using function module RRMS_MESSAGE_HANDLING (in variable-screen and in Web Template).

Testing the query in transaction RSRT1 will show the messages (3.x-Web Template) but not in the portal (7.x-Web Template).

Please can anyone give me a hint, what's the problem /what to do in 7.31?

Thanks in advance.