Unable to delete rows...

Hello.

I'm Using PostgreSQL v. 7.3.2 on FreeBSD 4.7-RELEASE-p7.

I was unable to delete several rows :

void=> select * from banners where banner is NULL;
id | count | max | banner_group | banner
----+-------+-------+--------------+--------
25 | 2328 | 10008 | 2 |
4 | 477 | 3336 | 33554438 |
(2 rows)

void=> delete from banners where banner is NULL;
DELETE 0
void=> select * from banners where banner is NULL;
id | count | max | banner_group | banner
----+-------+-------+--------------+--------
25 | 2328 | 10008 | 2 |
4 | 477 | 3336 | 33554438 |
(2 rows)

void=>

Is it bug or there are some errors in my queries ?

Thanks.

Krok.