SSRS Matrix Column Subraction



I am in Desperate need of a solution:

I am looking to Subtract Zdissenrolled Members from Enrolled Members (By month/status).  I am doing a count of members within a program(A,B,C) that have a status(Enrolled/Dissenrolled) associated with it in a given year/month (8/2013).

I can't come up with an expression that gives me the desired result.

I have tried this ... but it sums it

=IIF(Inscope("Dataset1"),SUM(Fields!MemberiD.Value),SUM(IIF(Fields!IntakeStatus.Value="zDisenrolled",Fields!MemberiD.Value,0))
-SUM(IIF(Fields!IntakeStatus.Value="Enrolled",Fields!Profit.Value,0)))