How do I get Cached Roaming Profile to load?

I have a 2008 server with a XP Pro client joined to the domain. I've set up Roaming Profiles. It works great. However I want to have the XP Clients have access to their cached roaming profiles when the domain is not available or they cannot access their profile share. The client has a cached copy of the users domain profile. However when I simulate a diconnected domain server, the client attempts to log on with a created temporary profile. How come it doesnt find the cached domain profile? Any help would be greatly appreciated!

Mark