A simple solution...

Inside of your OMS or FREEmidi setup there should be an ICON that represents your QUICKTIME music module -
sometimes during a new setup of either OMS or FREEmidi, a little RED sign comes across the QUICKTIME music little speaker/megaphone -
when this is on the ICON , this means that the QUICKTIME sounds are turned off...
To turn them on all you need to do is to double-click the ICON and there will be switch that you can just simply turn it back on..
Once this is back on - Your Quicktime sounds should be ready to play -
To test this you can use the functions
Test Studio - for OMS or
Check Connections - for FreeMidi