KPG-56D is the correct software for that radio.
There should be an FCC ID number on the back of the radio. If that is there, then it should be a North American market radio. If it doesn't have one, then it is likely from another market.
It's been a while since I touched that, but when you set up the programming software, it'll ask for a serial number. That should 056K44 followed by a bunch of numbers. That sets the programming software for the North American market. If you set up the software with that to match the market code in the radio, then it should work. But, like I said, its been a while, so I may be off.
Often what I've run into is people download the software from the internet and don't realize they are setting it up for a different market code.
The 'TUNING" and —PC— you are seeing says that the computer/cable are talking to the radio, but it's not liking something.
The other cause may be that someone touched the radio inappropriately with the wrong firmware.
These radios are a bit old, so my memory may be foggy. Don't trust this 100%, but might give you a place to start.