Table does not filter after adding measure

[colsen12]

I have the below relationship model:

When I display a table that has for example, Historical_ASP[Country Desc] & Historical_ASP[PH7] I can add a slicer based on Customer_Master[CUSTCOUNTRYDESC] and it will remove records that do not have that Country from the table. However, when I add the below measure for [Min Margin] into my table, the slicer no longer removes countries. Is this some type of relational problem? How do I get the slicer to work on a table with a measure in it? 

Min Margin = CALCULATE(MIN(Historical_ASP[Margin]), ALLEXCEPT(Historical_ASP, Customer_Master[CUSTCOUNTRYDESC], Historical_ASP[PH7]), ALLSELECTED(Historical_ASP[PH7]), ALLSELECTED(Customer_Master[CUSTCOUNTRYDESC]))