CASE Statement Help

All,

I need some CASE help to make the below statement work in the summary type on the results page on a saved search using a SUM function.

Formula Numeric:

count(distinct({entityid})) - (CASE   WHEN {activity.custevent_call_result} = 'Conversation' THEN 1 ELSE 0 END) + CASE      WHEN {activity.custevent_call_result} = 'Accepted TD Offer' THEN 1 Else 0 End

I was able to get the above formula to work. The problem is that the Summary type on the results tab will not allow a SUM. Is there a work around for this?

Thank you in advance for your comments/suggestions

***UPDATE***

I was able to work with NS support and trial and error to make this work. Below is the finished product to make the above work. NS did not like the double sum in the original statement. However by summing the items in the case statement there was no longer a conflict.