Countrows with Sumx not working

Hi guys,
I have the following data

Storage A has a capacity of 70. Now I would like to display in an additional table how many boxes in warehouse A still have free capacity. In the above example, this would be box A1 because 20 are still free, A2 is full with 70.

This is my Measure:

MEASURE =

VAR VAR1 = CALCULATE( SUMX( SUMMARIZE('STORAGE', STORAGE[STORAGE], STORAGE[BOX], "SCORE", sum(STORAGE[WEIGHT]), [SCORE] ))
VAR VAR2 = COUNTROWS(FILTER(DISTINCT(STORAGE[BOX]), VAR1< 70))

return VAR2

It works when I look at the box level, but when I want the total across all Storages, nothing shows up, so the total row doesn't match. What do I have to change?