SQL & PL/SQL :: Function Not Calculating

I am trying to create a function that when called will add the salary and commission a certain way to return an employee's annual salary.Here's my code

create or replace function Get_Annual_Comp
(Sal in number, Commission in number)
return number
as
[code]...

When I run the query, I get the proper rows return; however, my function does no calculation. If I input random numbers, I get the proper value returned. What I want is for my function to return the salary and commission of the employee specified in my select's where clause to be calculated as an annual salary.