Problem with vehicle

Hello, i make a custom vehicle in 3ds max and follow 2 tutorials:This and This

After i follow all the steps from video, i get one problem. I don’t know how to explain to you, but my tires get in ground and my tires are rotating but my vehicle don’t get speed to move forward. I search on all website to get a solution, i follow they response but nothing get

I make a video to explain the situation.