Rolling 12 Month Average

Thank you, I actually used that site to help try and diagnose my issue but still couldn't figure out my error.  My formula appears to be identical with the expectation he uses Variables. Also, my tables with the sales do not have daily sales, that's the only difference I can think of, but in my datesinperiod portion, I am using a continuous date table regardless.

I figured it out, I was trying to make the 12-month moving average a calculated column when it should be a measure. Thank you for helping me navigate this!