You either have 1 or 2 or both of these things set up wrong.
Its either your track routing or your exporting properties.
Its always one of these or both of these when you export and don't hear what you hear in a project.
Routing:Make sure Tracks go to buses.
Make sure buses go to the master bus
Make sure Master bus goes to the
Main outs 1/2 of your sound card. Exporting:Make sure you select 'Entire Mix' or 'Main Outs' as your export source.
Thank me,
CJ