After testing 3 hours now, I have a guess, but I need some infos before I can be sure. In the actual situation the col of the index, named CSSAPNR, is null for ALL records. When I insert some thousands of records in the empty db, the index is active. So
after inserting every record the index will be rebuild, I think I call the it index1. Now I deactivate and activate the index, I call it now index2.
Could it be, that index1 and index2 are different, because of the fact, that the col of the index is always null ?


Guido.