Maybe a post on the Captain sim forum would have provided quicker and more responsive replies....... Its dedicated to the model......
Reider
The CS forums aren't exactly the most friendly bunch, honestly.
As for the original post, are you saying your loading up a ground flight with the shuttle, and cannot start it up? That's easily solvable by one fact: It's not meant to take off.
Try slewing up into the air above the airport you wish to take off from (and at a good height, too; Try about 100,000 feet for a few minutes of flying). Think of the Orbiter as a giant brick trying to glide through the sky. It has no engines on re-entry, having used all of it's fuel during lift-off and for maneuvering in orbit.