Exchange 2k and Outlook Client

Hi, hopefully someone can give me some ideas. We use Exchange 2k Enterprise and Office 2k. When a user creates a message and types a name in the TO: line it doesn’t always resolve. These are names in our GAL.

For example John Doe is the name. If they type John Doe, it will not resolve/underline, but if they type doe, john it will.

Any thoughts? Thanks,