Previous year Week to date

Hey,

I am trying to create a week to date measure for previous year same day. Generally speaking my function (See below) works. But I do get blanks on random days. Would someone know why?

Function:

Net sales PWTD =

var __currentYear = SELECTEDVALUE( 'Calendar'[Year-Month Sort] )

    var __currentWeek = SELECTEDVALUE( 'Calendar'[ISO Week])

    var __lastDayNumberInWeek = MAX( 'Calendar'[Day of Week] )

    var __lastYear = __currentYear - 1

    var __prevWeek = __currentWeek

    var __output =

        CALCULATE(

           [Nett Sales],

            'Calendar'[Year-Month Sort] = __lastYear,

            'Calendar'[ISO Week] = __prevWeek,

            'Calendar'[Day of Week] <= __lastDayNumberInWeek,

            ALL( 'Calendar')

        )

    return

        __output

 

Result: