> Thanks a lot. The field ADOSEN.SUMME is a "computed-by" field.
> After turning it into a normal numeric field everything's
> working fine. Is this a bug?

Ask on IB_Support list, I dont know if Interbase/Firebird is intended
to support computed fields in this context. I do know that I have
noticed several anomalies/inconsistencies relating to computed fields.

Geoff Worboys
Telesis Computing