Firewire transfer from G4 to G5 not working

I am trying to transfer files from an older PowerMac G4 to a new PowerMac G5, but the G4 will not open as a target. When I hold down the "t" key, the G4 still opens normally into OS X. I just transferred multiple files from my iMac G5 (running the same 10.3.9 Panther version as the G4) to the new G5 (Tiger 10.4.3) with no trouble at all, and the iMac will still load as a target, so the problem seems to be with the G4. Any ideas? Thanks.