Formula usage with RBS and other enterprise fields

[Aaron Lance]

I'm trying to fill an enterprise resource text field with the last segment of
our RBS. We have an RBS 4.4.4.4.4.4 and I've set up a enterprise resource
text field with a formula that = right([RBS],4)

When it gave me an "#error" I backed up and tried it with a "local" outline
code and "local" text field, where it works fine.

I'm obviously not understanding a fundamental difference between outline and
text fields and enterprise outline and text fields.

Any help would be appreciated.