Function is Returning null

The following function is returning Null, any idea please ?

I have created a table in this function and insert a row in that table when
I call it, its returning Null.

Best Regards,

Luqman

 CALL FUNCTION2(5000,0,10,1999,2000)


 CREATE FUNCTION function2
        (principal decimal(12,2),
         rate decimal(5,2),
         startyear int,
         endyear int)
 RETURNS TABLE(
         DEP_YEAR INT,
         Begin_WDV DECIMAL(12,2),
         Rate DECIMAL(6,3),
         Dep_Amount DECIMAL(12,2),
         End_WDV DECIMAL(12,2))
 LANGUAGE SQL MODIFIES SQL DATA
        NOT DETERMINISTIC
        DISALLOW PARALLEL
 BEGIN
 DECLARE GLOBAL TEMPORARY TABLE MyFile
                (DEP_YEAR INT,
                 Begin_WDV DECIMAL(12,2),
                 Rate DECIMAL(6,3),
                 Dep_Amount DECIMAL(12,2),
                 End_WDV DECIMAL(12,2));
 INSERT INTO MyFile VALUES(1234,5000,0.10,12000,13000);
 RETURN SELECT * FROM MyFile;
 END;