How to drop primary key in Firebird 1.0.3 ?


I tried
ALTER TABLE AMETIGR
drop CONSTRAINT XPKAMETIGR;

but get message "index in use".

What may be wrong?

I also tried :

drop index XPKAMETIGR;

ALTER TABLE AMETIGR
drop CONSTRAINT XPKAMETIGR;

but still get message "INDEX in use"

Any ideas?