FI - FB01 - BSEG-ZUONR - the field does not be valued automatically

Dear all,

I've a BIG Priority 1, next Monday is the go live day!

During the booking FB01 Sap does not valuated automatically the field BSEG-ZUONR.

I’ve customized in OB16 with entry sort key.

I’ve customized in FS00 all gl account, and the flag sort key has been set with the sork key created

previously in OB16.

So, during a test, in FB01 using the GL customized and flagged with the sort key just customized

The result is that the field BSEG-ZUONR is blank!!

Please some one could help me?

Thanks again!!

Saverio