What is your "MOD Input " in your rig (I don't know what the 7300 calls it but the 705 uses this) Set>Connectors>MOD Input > set DATA OFF MOD to USB (or USB,mic) and set DATA MOD to USB.
I know there are some other rig settings in the Connectors group but I don't know what they are for the 7300. If you haven't set them....that's probably your problem. You have to tell your rig how to receive the modulating signal from the computer.
