Problem syncing documents with project server

[SD]

I managed to install project server 2003 on a SBS server
for learning purposes.

In Project Web Access under Documents, there is an option
in the left-hand pane to "Synchronize with Project
Server".

Selecting that gives the following error:
"The server running Windows Sharepoint Services failed to
connect to Project Server. Your changes will not be saved
into the Project Server database. Please try again later
or contact your administrator."

Any ideas why I'm getting this error, and what I might do
to fix it? I have no trouble creating new libraries or
new documents in the workspace.
Thanks in advance,
SD