How do I add an IF to this Business Rule

Summary:

Content (required):

I need to add an IF statement to the below rule to change the calculation based on Entity. (There is more accounts in the rule, this is just a snippet)

I'm missing something in the syntax, and have compared to some other rules, but can't figure out what I'm missing. I have tried a few things but get different errors each time.

Errors:

1. The CALC command [IF] can only be used within a CALC Member Block Rule
2. Error compiling formula for [BU0, at or after line: [" FIX ("DREV")"]] (line 14): operator expected after [FIX]

Any suggestions welcomed.

Version (include the version you are using, if applicable):