Now I've upgraded to Outlook 2007 why won't Activesync work?

[Revolve]

I have been successfully synchronising an iPaq 4150 with Outlook 2003 using
Activesync 3.7.1 on the PC and Windows CE 4.2 on iPaq. Now I have just
upgraded to Outlook 2007 it will no longer synchronise appointments or
contacts.