Rolling 30-Day Average

Hi all,

We're trying to create a rolling 30-day average in one of our bar chart widgets. I've tried using different solutions found online, but they all involve RPAVG, CURRENTDATE or other window functions that seem to break our connection to the live model or throw an unexpected token. An example we found was the following:

AVG( [ Total Value], RANGE ( PREV ( [Days in Date], 30 ), CURRENT([Days in Date])))

from which we got the 'not supported by Live Model' error. 

I've also tried repeatedly adding together ( [Total Value] , PREV( [Days in Date] , n)) from n=1 to 30, but this seems to overwhelm the widget and break connection with the model (though it works in theory, I did get it to work with smaller n, such as 5)

Any help would be greatly appreciated.