Hello Cetin, thanks for your reply.
Indeed I was talking about newid(). I copied the code from VFP (incl ids.dbf table1/2.dbf en the storedprocedure) wich worked fine, until I tried to add a third table to it. I now still can append blank on table1 and table2 (the copied tables) but not on table3 wich has the exact same fields, type, widths and index as one of the copied tables (for example table1.dbf).
I hope you can help me some more with this.