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.