Passing Year and Month parameters using Stored Procedure

[Desperado]

Hi,

I'm using a stored procedure for my report. The stored procedure is passing  some parameters. Every other parameter is working for me , But Year and Month parameters are not .. I have to use these two parameters in the drop down and month will be cascaded to year. if i'm using these two parameters from the stored procedure for year and month , No rows are returned from the drop down. But, if i'm doing the same using filters at the report end , i can see the data in the drop down. the client wants me to use the year and month columns from the procedure.
How to use these in the value prompt to get the data displayed.. Am i doing anything wrong ?? is there any other way ?

Thanks in Advance