[Exim] Order doesn't matter?

Hello,

It isn't really clear to me, but I'm having this problem:

I have a local user, "joe", but I also have a user "joe" within a virtual
domain. Mail sent to "joe@???" shows up as "joe@???"
instead. This is a rather serious problem for me at the moment, and I was
wondering if someone might be able to provide some quick inspiration.

How do I make the Virtual director take precedence?

Thanks,
Christopher