CALCULATE BASED ON A STATUS

Hi,

We have Units in Wells and we need to calculate the average lateral length of the unit based on how many wells are in the unit, and what their lateral length is, but only for a certain status of well.

So some wells are producing, some wells are being drilled. We can only calculate the producing wells.

For instance in this screen shot we have 3 wells in the unit, but only 1 of them is Producing (BM STATUS IS PDP).  So technically the average is the lat length of that one PDP well. (or if there were 2 PDP, etc).

This is the current formula - I put the first part thinking that would work - but it only SHOWS the average on the PDP well, not calculate if it is a pdp well.
If([BM STATUS]="PDP",[UNIT - TOTAL LAT LENGTH]/[NUMBER OF WELLS IN UNIT-SUMM])

Any ideas is greatly appreciated!