Does the Stock, built in campaign work correctly?
Can you fly the built in SINGLE/TRAINING missions?
If so, then it probably isnt a graphics problem..
Another thing you might try is copying one of the Valhalla Campaign missions from the Campaign/Mission folder into the FA-18/Mission folder and fly it as a SINGLE mission.
If that works, then I can only go back to my first guess about some files not installed in the right areas.