problems synchronzing items between project server and sharepoint

[Richard]

I've a problem synchronizing issues between projectserver and sharepoint.
When I click 'synchronize with project server' in a sharepoint list I get 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."

I don't no what is going wrong and where to find it. I'm logged in with a
useraccount with domain admin rights. The account is also sharepoint admin
and projectserver admin.