Cubase 5 MIDI out port in the MIDI track and External Instrument problems

Hi, I know my stuff is old but it should not matter, probably I didn’t notice something during the setup…
I used Cubase 5 and imported one MIDI file already, I want to use external synth’s (Korg Triton) sound to finally render to another audio track.
I checked all the cable setting right (MIDI In/Out, Audio In/Out to my MIDI controller), and I can see my MIDI controller interface (M-Audio External…) is active in MIDI-Device and Vst instrument setup, too.
But in the MIDI-out port of the MIDI track, why I cannot see my M-Audio interface? (I only see other soft-synth…)
After that I add one instrument (Triton) in the Instrument setup menu. Now I can see there’s a “Triton” in the MIDI-out port, but when I assign “Triton”, add another audio track and try to record from my external instrument, still no any signal appeared… (I checked my Triton “Local control” is off.)
How shall I solve it, is there’s anyone can help? thanks.

Are you setting up an external instrument in VSTconnections?

Yes, I did set up the external instrument in VST connections.

The track output would be set to your external instrument - Triton.
You need audio cables going from the Triton to your audio interface, not your midi controller.
That’s what’s set up in VSTconnections under the external instruments tab.
Hardware audio inputs and midi output.
Use Instrument track instead of midi track.