Cumulative count for missing data

Hello, 
I am trying to figure out how to calculate a cumulative count where, if a category returns 0, it will take the "previous" value. I have tried a couple methods but it doesn't seem to work. This must be a measure due to the size of the data set. 

This is my current DAX:

Cumulative Tester =
VAR _Count =
    CALCULATE (
        DISTINCTCOUNT ( Data[OrderId] ),
        FILTER (
            ALLSELECTED ( Data ),
            Data[DaystoRespond] <= MAX ( Data[DaystoRespond] )
        )
    ) + 0
VAR _Total =
    CALCULATE ( DISTINCTCOUNT (  Data[OrderId] ), ALLSELECTED ( Data) )
VAR _AccountForZero =
    CALCULATE (
        DISTINCTCOUNT (  Data[OrderId] ),
        FILTER (
            ALLSELECTED ( Data ),
            ( Data[DaystoRespond] - 1 )
                <= MAX ( Data[DaystoRespond] ) - 1
        )
    ) + 0
VAR _NoBlankCount =
    IF ( _Count = 0, _AccountForZero, _Count )
RETURN
    // DIVIDE(_NoBlankCount,_Total)
    _AccountForZero

This gives me the following result:

The intended result should be that, on row 26, the result should be 12948, instead of 0. 

Would anyone be able to help?

Thanks!