Slicer based on sum of field in Matrix

[FrustratedUser3]

I am trying to create a simple slicer based on values in a Matrix, but I'm guessing that because the values are a SUM of decimals it is not working correctly.

My matrix is displaying Time Entry values using a field called "TimeEntered". This is a decimal number and was set as a Sum so that each time entry for a particular date is added up and displays in the matrix, this is working fine.

How can I create a simple slicer to show two options:
"Time Entered" - filter the matrix for all sum of TimeEntered field greater than or equal to 8 hours

"Time Missing" - filter the matrix for all sum of TimeEntered field less than 8 hours

Here is the calculated column I have tried:

ColumnTEST = IF(SUM(TableName[TimeEntered]) >= 8,"Time Entered", "Time Missing")

And it seems to be working for the individual data if I view the table directly, but in my slicer it does not work. Do I need to create a measure first somehow differently than what I am using above? Or is there any tutorial I can be pointed to that would show how to accomplish this simple task?