Variable Screen not coming while passing default values in variables

Hi Experts,

We are using BI7.0 and Bex 7.0 and CRM 7.0 version.

We designed a query in Bex Query Designer.In that Query We having characteristics variables which are ready for input from user end.

We have also passed Default values in Variable.

We have added the report in CRM WebUI portal.

Issue is that:-

While executing the report from portal variable screen does not appear.

But when we remove the default values of  Variables in Bex Query Designer then variable screen appear in report for user input.

But we want variable screen should appear while passing default values in variable also.

Please guide us.

Thanks & Regards,

Arpit Gupta