Weird NULL behavior

Hi:

Has anyone encountered this before?
SELECT CAST ( (NULL*NULL) AS NUMERIC(2,0));

returns the following error message:
Cannot cast type '"char"' to '"numeric"'

But the following sql statements returns NULL:
select NULL:
select NULL * NULL;
select cast ( NULL as NUMERIC(2,0));

Thank you in advance,
ludwig.

__________________________________________________
Do you Yahoo!?
New DSL Internet Access from SBC & Yahoo!
http://sbc.yahoo.com