Fargol

My question is incredibly basic and possibly stupid - How do I record something I play on my keyboard into MixPad. I have a Korg SP-280 keyboard and a USB Midi cable. I've attached the cable to the IN and OUT ports on the keyboard, and then into a USB port on my desktop. MixPad appears to recognize it (it shows as "USB2.0-MIDI" in the File -> Options -> Midi Controller tab). Under Audio Options I assume I need to check "Recording Using a Midi Device", and in the dropdown I selected the aforementioned USB2.0-MIDI choice. I've Enabled recording on Track 1. When I click the "Record" button I get a popup saying (paraphrased) that for Track 0 I chose USB2.0-MIDI but I've configured it as a Hardware Controller, and suggests I disable that. So I do that (under File -> Options -> Midi Controller tab I unchecked "Enable MIDI Hardware Control". Then when I click the Record button, absolutely nothing happens. No errors, no warnings, and no recording is going on. If I select as the recording device the microphone on my webcam, it records fine but of course I'd prefer the Korg. Any help greatly appreciated. Thank you.