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