Executing a procedure from SQL Plus

I created the package and package body below. When I call this from my Visual Basic app using ADO it runs fine. When I try to execute it from SQL Plus I get the following error. Am I doing something wrong.

--
Error ----------------------------------------------------------------------
---------

SQLWKS> execute Personality.GetNames('B%');
Personality.GetNames('B%');
*
ORA-06550: line 2, column 2:
PLS-00306: wrong number or types of arguments in call to 'GETNAMES'
ORA-06550: line 2, column 2:
PL/SQL: Statement ignored



-- Creation of package and package
body -----------------------------------------------------------------------
--------------

CREATE OR REPLACE PACKAGE Personality
IS
   TYPE PeopleCur IS REF CURSOR RETURN sti_personnel%ROWTYPE;
   PROCEDURE  GetNames(PeopleCursor in out PeopleCur, plastname in
sti_personnel.LAST_NAME%TYPE);
END Personality;



/



CREATE OR REPLACE PACKAGE BODY Personality
AS

PROCEDURE GetNames(PeopleCursor in out Peoplecur, plastname in
sti_personnel.LAST_NAME%TYPE)
   IS
   BEGIN

   OPEN PeopleCursor FOR
     SELECT * FROM sti_personnel WHERE LAST_NAME like  plastname ;

END GetNames;

END Personality;



/




Thank you,

David