%addr <> *null vs %parms >= ?

If the prototype for the export procedure in a service program is as below:
D $get905PgmAut   pr                       
D  userID                       10    value
D  pgmNam                       10    value
D  autToAdd                       N        
D  autToUpd                       N        
D  autToDlt                       N        
D  autToPgm                       N   OPTIONS(*NOPASS)

Should the following two if blocks get the same result?
If    %addr(autToPgm) <> *null
 ... do someting
endif
 
if    %parms >= 6
... do something
endif
 
 
I getting the Pointer not set for location referenced error when using %addr.  
However, It does not happen all the time.  Sometime it work.  Sometime it 
doesn't.