db2 dbexpress delphi7 error

Hi,

we have a running application (delphi6 and dbexpress for db2).
With delphi7 the same application cannot save any record.
We always get the message:

[IBM][CLI Driver] CLI0126E  Operation invalid at this time. SQLSTATE=HY011

It seems there is an problem with transaction isolation,
but DirtyRead, ReadCommited, RepeatableRead - we get the same
error.

Whats wrong?

WinXP Professional
Delphi 7 Enterprise
DB2 7.2 Fixpack 7

Regards,

Frieder