Trying to use the forecast value in chart properties but getting the error

user14700

I'm trying to get a forecast of quantity of sales for the current month using the last value projection in the chart properties. When I select the Forecast Value option, I get this error: 

An issue has occurred during processing. We are unable to complete the request at this time. 

 

Why am I getting this and how do I get around this? It only occurs when I select the Forecast Value, any other option works fine.

 

BrendanH

 

Are you using a beastmode as the forecast value?

user14700

Yes I am. Is that the reason why it's not working?

ST_-Superman-_

Mind sharing the beastmode?  Might help understand what is going on

user14700

Here it is:

SUM(
  CASE WHEN `Win Date` IS NOT NULL THEN 1 END
  )