Calculate function not respecting filter

Hi,

I'm trying to create a measure (#2) based on another measure (#1).

Measure1 = CALCULATE(sum('DATA'[Amount]),'DATA'[Account]="Revenue")

Measure2 = CALCULATE([Measure1],'DATA'[Category]="CATEGORY1")+ CALCULATE([Measure1],'DATA'[Category]="CATEGORY2")

(Category is a calculated column in DATA that returns a category based on a related field in another table)

Measure2 correctly populates revenue for CATEGORY1 and 2.  The problem: for some reason, Measure2 is also populating CATEGORY1 & 2 totals for categories that have no revenue (that aren't CATEGORY1 or 2).  Can anyone help me understand why calculate is behaving this way and/or how to fix?  Many thanks!!