Autocomplete Rule - Nullifying Grade on Worker Assignment

I am trying to create an autocomplete rule that will nullify grades when the job doesn't have a grade associated to it. I have grades associated with 10 different countries and I'm trying to have the autocomplete rule look at the specific business unit that is tied to the employee and look for a grade. If the grade doesn't exist I'd like the autocomplete rule to nullify the grade. Below is a screenshot of the rule I've created thus far but is unsuccessful.