Unable to login after enabling mobile account

Before PHD syncing can work, the user must have a valid network home folder. Your post above doesn't say whether that is the case. My experience w/ 10.6 server is that creating a user record in workgroup manager is not enough. If all you've done is create a user record in workgroup manager, the user will try to login on the workstation, but will get the "head shake" at the login screen and not succeed. You must first (on the server) specify a network home directory, and click the button to create that home directory (all done in workgroup manager in 10.6 server). Once the network home directory is created, then the user can login at the client workstation. After that, you can go thru the process (at the client machine) of changing the account to a PHD account.

If you already have users with local accounts on their laptops that want to use PHD syncing, it's more involved. You must create a network home for them on the server, in workgroup manager specify the location of their network home. Then move all their local files to their new server home folder (don't user finder copy for this, use rsync). On the server, chown all their files to be owned by the server userID that belongs to them. Verify their files arrived corectly on the server by having them login from another client using their server credentials, and verifying that their stuff is all there correctly when connecting as a network home user. Then destroy their local account on the laptop, including deleting the userID from system preferences. Then have them login to the server as a network home user from the laptop they are going to own. Then on the client, go thru the creation of their PHD replica. This process is complicated, because if they were a local user, their userID us probably #501, 502, 503, etc. On the server, their UserID is likely #1001, 1002, etc. Under the hood, it's the UserID number that needs to be consistent across the network.