Power Pivot :: Create Measure That Returns A Subtotal

I'm working on a measure which I'd like to use in PowerView, my data model contains 2 things:

1) Employees' scores
2) Stores in which employees work in

I would like to be able to put the employee's score in comparison to the store average (which is the average of all the employee's scores in the store), and then provide every employee with an individual report on their scores against their store's score (by tiling the view in PowerView by Employee). To do this, my (first attempt) at a measure for the store average looks like the following:

Overall_Avg:=CALCULATE([Score], ALL(Employee[Name]))

Which gives me the score of the employee vs. all other employees across all stores. What I'd like to then achieve is to add an additional filter that filters only the scores for the store that the employee belongs to - which is where I'm stuck.

Here are some of my attempts at them

Store_Avg:=CALCULATE([Score], ALL(Employee[Name]), FILTER(Employee[Store] = Store[Store Name]))

returns an error for me. However, trying:

Store1_Avg:= CALCULATE([Score], ALL(Employee[Name]), FILTER(Employee[Store] = "Store 1"))

works perfectly, but doesn't give me the desired output, which is 1 measure that changes the store depending on which employee (and thus store) is being selected.