Create Trigger to record changes - Incorrect syntax

Hello,

we are testing with version 9.1.1 to plan the update next year. We are now facing the following problem.

In the DBQueue remains the DBQueueTask "Create Trigger to record changes" (UID_Task=QBM-K-CommonMakeWatchtrigger) with BaseTree as UID_Parameter.

Looking into the system log the following message appears:

(execute slot single)50000 0 re-throw in Procedure QBM_ZTriggerWatchCreate, Line 8
50000 0 re-throw in Procedure QBM_PTriggerWatchCreate, Line 85
50000 0 re-throw in Procedure QBM_PSQLCreate, Line 27
50000 0 re-throw in Procedure QBM_PExecuteSQLWithRetry_LLP, Line 21
50000 0 re-throw in Procedure QBM_PExecuteSQLWithRetry_LLP, Line 13
156 0 detected in (SRV=xxx, DB=xxx) Procedure GEN_T5FD175F854D38DD360AB37FA6, Line 401
156 0 Incorrect syntax near the keyword 'union'.

What does this error message mean? Which syntax seems to be wrong?

What should or can we check so that we can correct the syntax so that this error no longer occurs and this task can be processed successfully?
can be processed successfully?

Thanks for any advice