Wrong query execution.

Hi,

It is possible that I am wrong, but I can nof find my mistake.

I have this 2 querie:

 delete from a_grad  where ids NOT in ( select KL.IDS_GRAD from
a_klienti kl  ) ;

 It returns 0 rows are deleted !

And the second one:

 delete from a_grad  where ids IN (select G.IDS FROM A_GRAD G WHERE NOT
EXISTS ( select * from a_klienti kl where KL.IDS_GRAD = G.IDS) ) ;

 It returns 356 rows are deleted !

I expected that the first will delete also 356 rows.

I am using pg 7.3.1 ( I got the same result on pg 7.3) running linux rh
7.3.

All IDS and IDS_GRAD are declared as name and do not exists any null's.
The encoding is unicode.

Pls. help me to resolve the situation.

Regards,
ivan.