Trouble connecting MiniMac to TV

I am trying to use my Samsung HD tv as the minimac display using HDMI. It is a PowerPC G4 1.5 GHz processor. when i plug the minimac into the HDMI the tv recognizes it and displays the message. "The resolution is not supported on this TV. Please change the resolution." how could i go about fixing this? i know the minimac and tv will support 1440x900 so i am bewildered. i am working with an old minimac and the tv is under 1 year old if that makes any difference. any suggestions? sorry if this is in the wrong section.

TRy a lower resolution like 1280 x 960 or 1024 x 576, connect up the TV and then change the resolution up once you get a screen you can see as a start

that is the problem i dont get a workable screen, its just black with an alert message box.