Logic Pro 9 New user, Logic express 9 with protools HD question

[zenguitarguy]

Hi! I am trying to help a pal and have installed Logic express 9 on a mac intel running 10.6.3. I can see the option in Logic preferences to allow the Digi HD as the I/O and when I hit the KBD am seeing notes/midi in the bottom window, but no sound...am I missing something here? is this possible? I hope so...lol

Thanks in advance!