I think your problem is that you didn't snap your rail curves to your profile curves. Hold down the V key, and gesture with the middle mouse button. Here's a video on the alias site demonstrating the proper use of the birail 2 tool. You can check out demos of the other tools too.
Good luck and have fun.
Many of life's failures are people who did not realize how close they were to success when they gave up. --Thomas A. Edison