Get previous value from indexslicer dynamically with double filter context

I am creating a report for which I use and index slicer. I want to compare a value from the current selection with the value previous to the current selection. Below you'll find an example of my data. i want to create a measure that shows me the value for the "money" from the selected index value and the index value previous to the selected one. Also i want to have a measure for the text value from the selected index value. 

I tried the formula below, but it does not seem to work. I only get a value for selected index filter, but not for the previous one. Can somebody help me? 

Previous score = 
CALCULATE( 
SUM( 'subject_score'[Score]),
 Index[index] = MAX(Index[index) - 1),
 FILTER('subject_score', 'subject_score'[subject] = "Money"))

Thanks!