Bex Query "No data to fetch"

Hello Experts,

I am having some trouble with a BEx Query. I will first tell you the requirement and then explain my problem.

Requirement: 2 Variable. (One for Customer Number & Second one for the "No. of Weeks"). Based of the these 2 variable system need to calculate the from week and to week and get the sales data. This query needs to be implemented as WebServices using the universe and QaaWS tool.

The query we have created works perfectly fine using RSRT transaction. It ask for 2 input parameters and provides the result based on the input parameter.

Problem: When I use this query as a WebService, it works fine when I only provide the customer number. In this case the query takes the default value of the "No of Weeks" parameter and works perfectly fine. When I provide both the parameters it returns "No data to fetch".

I don't know what is the issue. The 2nd input variable has been defined as Formula Variable and Customer Exit.

What can be the issue here?

Regards,

Himanshu