Variable not working correctly in measure

I am using a variable in a measure to find which item is selected in a slicer. The variable is called ResultGroupNumber. I want this to be calculated based on the value in the slicer. If I test the ResultGroupNumber and calculate it and then add it to a card I get the number 9 which is correct for the current value in the slicer. Here is my formula I am using below. Basically, I am trying to find the average of a students results for all resultgroups which are less than the current one selected

LPAveLongTerm = 
    var ResultGroupNumber = calculate(max('Result Group Table'[Sort Order]),allexcept('Result Group Table','Result Group Table'[Result Group]))
RETURN
calculate(AVERAGE(uncRedshift_Studentresults[LPResult]),filter(all('Result Group Table'),'Result Group Table'[Sort Order] < ResultGroupNumber),allexcept(uncRedshift_Studentresults,uncRedshift_Studentresults[NameNum],uncRedshift_Studentresults[ResultType]))

 When I use the variable I get 

However, if I remove the variable and use the constant 9 like this

LPAveLongTermV2 = 
    var ResultGroupNumber = calculate(max('Result Group Table'[Sort Order]),allexcept('Result Group Table','Result Group Table'[Result Group]))
RETURN
calculate(AVERAGE(uncRedshift_Studentresults[LPResult]),filter(all('Result Group Table'),'Result Group Table'[Sort Order] < 9),allexcept(uncRedshift_Studentresults,uncRedshift_Studentresults[NameNum]))

I get the second column which is what I am after.

How can I get the slicer to determine the variable rather than hard coding a number in?

Any help would be appreciated.