This expression works fine. However where "Department Name" is I want a variable based on a cycle group (which is the dimension in this object). So each time the cycle is changed it is reflected via a variable in the expression above.
It appears that it works for selections (within the cycle group) that do NOT have any spaces. It doesn't work for selections such as "Line of Business". I tried $([vRetensionDimension]) with brackets but that didn't seem to work.