Report Writer - Using Formula in a set

Hi I am trying to learn Report Writer (GR31) and one of the things I want to do is put a formula in a set, but I am having hard time getting it to work.

I want to put a formula like this...

if account is 5000000 then put do one thing else put 1

IF '&ZACCT1' = 500000 THEN '001' * 'A' ELSE 1

but I am not getting any value back.

Anyone have any idea what I am doing wrong.

Thanks in advance for any help/suggestions.

John