Can't get sound from Midi Guitar into garage band

Hi, I have purchased Midi Guitar for garage band but can’t get any output from it. i’m using a Scarlett 2i into a MacBook pro and garage band of course. What am i doing wrong?

In short you just enable the MIDI Output module and select the Virtual MIDI Output. Then MIDI is automatically picked up by Garageband.

Please see the help page and video here:
Its the same for the MG4GB version.