Rate between tables

Hi Dale,

 I've uploaded a dummy file here. My end goal is to have a gauge where if I select a data range, operator and type of failure the value will be the average of the rates for all the months. included in the data range I selected. At the moment the value shown by the gauge is simply the sum of the rates, and not the average. As I understand it, there are currently 2 issues:

1- value is a total and not the average of the monthly rates

2- even if the value was an average, since the Rate measure doesn't return any value for months where there were no failure events, the average would be wrong. I need Rate measure to return "0" every month when there are no failure events.

Thank you!