Filtering account by UD's

I am creating an alternate roll-up of our accounts for some specific reporting which requires that certain accounts only return data for specific departments.  What is the best way to do this?  I tried using a dynamic calculation to create new accounts that filtered on UD2 but it did not return any data.  The formula that I used was   Return api.Data.GetDataCell ("A#61550:U2#Dept48")