previous month not working with hierarchy slicer

i created 3 columns year quarter and month (they are created from my date column) to use them in hierarchy slicer

when i choose a date from hierarchy  slicer endofmonth works

CALCULATE(SUM('database'[customers]);ENDOFMONTH('database'[date]))

but previous month does not.

 (previousmonth gives the right value eg if i select from hierarchy slicer 02/2016 it shows 29/01/2016 but calculate show 0)

CALCULATE(SUM('database'[customers]);PREVIOUSMONTH('database'[date]))

if i select a month from the default slicer (with the original date) everything works fine.