If you have the ability to connect the computer to the FP-4 via MIDI, you could play the 'MIDI out' to the FP-4 then run an audio cable from the FP-4 to the Line In on the computer and record the audio. Otherwise you'll need a softsynth to play (and render) the MIDI to audio. Do this by selecting a blank track, changing the track type to audio (via right-click), then rewind and hit 'record'. This will likely give you the best sound reproduction of your performance since you played it on that keyboard.

If you hit 'Play' in PT do you hear the song play?
If so another option is to record what you hear when the song plays.
Set your Delta to 'Input Monitor', go to PT and go to Options - Preferences - Audio and select the Delta Input Monitor if available, otherwise select 1/2 input. Again click 'move selected device to top'. Maybe then you can record what you hear as it plays.

I do not work here, but the benefits are still awesome
Make your sound your own!