using if function to compare 2 columns

having a bit of difficulty trying to compare two tags %artist% and %albumartist%
basically i want to create a new column that i can use to sort all tracks where these 2 tags are not the same

created a new column 'test'

value = $if(%artist%=%albumartist%,'ok','problem')
field = blank

but it returns 'ok' for all tracks ???
looked in help and on forums but not having much luck



In general I would solve such a task with a filter:
"$if($eql(%artist%,%albumartist%),1,0)" IS 1

Thanks for the prompt help my function building skills were not quite up to it
works well and with 13k of tracks its going to make it a damn sight easier to fix my tags