DELETE Statement won't work correct

[SoftIl]

Hi,
what's wrong with this statement:

DELETE FROM behandlungsliste BHL, basisliste BL WHERE ((BL.betriebs_id =
'15427782-c133-11d8-a802-0010b53f93f1') AND (BHL.masterrec_id =
BL.record_id))

If I call this statement, all records in table "behandlungsliste" are
deleted.
I would like to delete in table "behandlungsliste" only the records for
which the condition is true?
How is the correct statement?

Thanks for your help
Carsten Ilwig