About my MiDiPLUS X2mini connection sound card five-pin interface to Cubasis3 problem

I now understand how to use MIDI Learn. My main problem is that my miDiPLUS 2Xmini external one can’t be played incubasis3. When I press it, there is no response. Whether I directly connect the midi keyboard transmission cable through the otg converter or through the sound card five-pin interface, it is always just that the sound card is working normally. The external midi device can’t work.