dd if=/dev/null of=/dev/hda does not work

From: Johannes Lebek (reply-to-newsgroup_at_domain.com)
Date: 04/29/04 

Date: Thu, 29 Apr 2004 19:16:13 +0200

Hi there,
I try completely erase all data on my harddisk drive.
Tried the command mentioned in the subject. Ran it from a rescue disk.
Does not work as expected. Output is:

0+0 records in
0+0 records out

Give no example. What did I miss?
Any help is appreciated.
Thanks in advance,

Johannes