Aggregation in CASE statement

Hi All,

I am trying to achieve this in my CASE statement however i am getting "Cannot mix aggregate and non aggregate comparisons or result in CASE expression" . Is there an alternate way/approach to achieve this ?

CASE [Numerator]

    WHEN "DAYS_CREATION_DISCOVERY"

        THEN SUM([Days Creation Discovery])

    WHEN "DAYS_SUBMISSION_CREATION"

        THEN SUM([Days Submission Creation])

    WHEN "DAYS_CLOSURE_CLOSURE_REQUEST"

        THEN SUM([Days Closure Closure Request])

    WHEN "EVENT_COUNT"

        THEN COUNTD([Event Count])

   ELSE NULL

END

Thanks.

Shariq