fms for EDG1 and OeDG

Hello,  I would like to ask you to help me with one formatted search. >Stock Management ->Special Prices ->Discounts Group->Specificic BP.

I  created

SELECT CASE

WHEN $[EDG1.Discount]  IS NOT NULL '' THEN $[EDG1.PayFor] ='0'

ELSE $[EDG1.PayFor]  ='1'

END

but it doen´t work.

I would need to help.Thank you, regards Martina