Cumulative count by filter issues

Hey,

I have a cumulative measure which works fine in theory, but it has the additional complexity of the ability to use a legend. I am using it to get a count of actions by weeks to an event, and there are multiple events.

Here is the DAX:

Cumulative Bookings by event=

     CALCULATE(count(bookings),

            FILTER(

                ALLSELECTED([Weeks to Event]),

                           [Weeks to Event] <= MAX([Weeks to Event])

                ),

               VALUES([Event])

         )

And it almost works...

But as you can see, where a event doesnt have data for e.g. 22 weeks to the event, it just shows the total bookings. I would like it to be 0 in this case.

Can anyone see where i need to change the DAX to fix this?

Thanks,

H_Jones