Software Update Server

I am having a problem with a server running 10.4.7. After I have enabled Software Update server, clients who check against it say there are no new updates even though I know there are. If I check with Safari to see what updates are visible, they are all present, but clients do not show anything is available. If I fail back to Apple, everything works fine. The Software Update at the clients show my Server's IP and the server says it have 122 updates mirrored and enabled. The logs show no errors and the clients get no errors when they check. The only two things that bug me are... 1. This is not setup as an OD, just a standalone server and 2. Tiger was installed by upgrading a Panther Server Installation. Can anyone help?