SQL & PL/SQL

There must be something I am doing wrong but I can't figure it out. I have a stored procedure like the following (this is a simplified version). The query out of the Proc runs without any errors and the procedure appears to run correctly (I get a "PL/SQL procedure successfully completed" message and I show no errors), but when I try to print the output I get the errors shown on the subject line of this thread.

The simplified Stored Proceedure is:

IS
Subno schemaname.Tablename.columnname%TYPE;

Cursor Purge IS
SELECT schemaname.Tablename.columnname
FROM schemaname.Tablename
WHERE (schemaname.Tablename.columnname='44933');

BEGIN
OPEN Purge;
LOOP
FETCH Purge INTO Subno;
EXIT WHEN Purge%NOTFOUND;
END LOOP;
Close Purge;

end;

I then try to view the results with the following lines and I get the errors:

set serveroutput on;
variable Purge refcursor;
exec schema.StoredProcName;
print Purge;

This seems very simple but there must be something I am missing. Any help would be appreciated.