Passing variables between sp's

So I'm doing a select in one stored procedure and trying to pass a parameter from the one into the other.

CREATE PROCEDURE usp_select_for_class_code
@numberList int output
AS

SELECT @numberList = waco_dir_class
FROM agcwa_membership
execute usp_classCode

But I keep getting told that

Procedure 'usp_select_for_class_code' expects parameter '@numberList', which was not supplied.

Any help please