ssrs-date range parameter to cube

Hi,

I need to pass the date range as a parameter to the cube data,so that i will get the data between the given range of dates.

so I checked  the parameter option in the query designer and changed the parameter datatype to datetime and executed the query.

I am getting an error  as

" The restrictions imposed by the constrained flag in the STRTOMEMBER function were violated"

Kindly help !!

Thanks

Esmari