Analysis :: Limiting Sum Function To Only Evaluate The Data In Slicer

I am having trouble limiting a sum function to only evaluate the data in the slicer. I need a sum of data calculated per employee and when there is a slicer of one employee my measure still evaluates all employee. For example:

WITH
MEMBER [Measures].[TotalEmpHours] AS
SUM([Employee].[Employee].members, [Measures].[Actual Ovt Hours])
select
{
[Measures].[TotalEmpHours],

[Code] ....

The above reports the overtime for one employee in [Measures].[Actual Ovt Hours], I expected [Measures].

[TotalEmpHours] to be the same as there is only one employee in the slicer select. The real measure is the minimum of two values for each employee.

This is a simplified example but I think it should work.Is there another construct to iterate the employee set? I have no control over the query as it is from a pivot grid. If the filter (employee) is leftmost in the row area, then it works because the employee ends up in the row part of the query.