CASE Statement WHEN add multiple fields

SOLVED

I am looking for a CASE statement to replace an excel formula.

Excel formula would be: =IF(TDMMYY="0816",(N2+O2),IF(TDMMYY="0916",(N2+O2+P2),IF(TDMMYY="1016",(N2+O2+P2+Q2))))

The one I'm trying that is failing is:

CASE

WHEN "CI_UDT_ITEM_SALES_PROJ"."TDMMYY" = '0816' THEN [0716]+[0816]

WHEN "CI_UDT_ITEM_SALES_PROJ"."TDMMYY" = '0916' THEN [0716]+[0816]+[0916]

END


I've tried several variations without success.