Query as a web service parameter passing problem

We are facing a problem using QAAWS in Xcelsius to make the dashboard dynamic.

In QAAWS when we are passing any number parameter like week it is fetching the data but when we are trying to pass any character value like month or date format its not fetching any data.

I want to know what is the problem, is the problem with Xcelsius or it is a BW cube issue whose data type is not matching with BO universe datatype?

Please help.