OK - you've created your track, and when you play you can see the MIDI events being recorded? Great - that's the crucial bit.
Have you actually told Logic what sound you want to play? I don't know what you have installed on your system in terms of samples, or synths or other VSTis, but In Cubase - what I use, you can create a track then open a VSTi and make the MIDI track talk to it, or just open a sound source from a list, that creates an instrument track, which is just a different kind of non-audio track. What sounds are you trying to make it work with? A MIDI track has an input and an output. Sounds like the input is connected, but you haven't got an output yet? If you have - then it will be a routing issue. Perhaps the sound you have picked is not routed to an output?