12 Month Sales

Hi

I have created a measure to sum sales over past 12 months, before August 2017

I want the measure to calculate the previous 12 month sales from a date that is selected in a slicer (Dates Table0

Measure = CALCULATE(sum(EOM_STK[Sales]), 'EOM_STK'[perioddate]<=DATE(2017, 08, 1) && 'EOM_STK'[perioddate]>=DATE(2016, 09, 1))

Dates table

Year   Month  FilterDate

2017  01         2017-01-01

2017  02         2017-02-01

etc

if I substitue the dates for the date slicer, I get the error message that the expression contains multiple columns but only a single column can be used in a true/false expression. What am I doing wrong?