Make sure the Magma "ExpressPCI UL2S Enabler" has been installed and is active in the Extensions folder. Make sure the PC card is firmly inserted in the PC slot on the right side of the G4, and reboot.If you are using a Mix Core alone or a Mix Plus, the Core card should be intalled in the topmost slot in the chassis. In the case of a d24 and Mix Farm combo, the Mix Farm should be in the highest slot, and will be recognized by Pro Tools as a Mix Core.It should be noted that the only Digidesign supported card configurations for this chassis are Mix and Mix Plus.