PDMWorks 2007 Vault with 2008 Client?

I've installed 2008, and was trying to get parts from our2007 vault, but I can't seem to log in to the old vault. I get nofeedback after entering my username/password, it just pops up thevault/ server version page and then doesn't log me in.

Are they simply not compatible?SolidworksWorkgroup Pdm