Rail Grinding System not working?

Hello. At the time I made this post, I had a problem with my rail grinding system. I used BodyPositions and it just went out of the track. I put borders around it, but it didn't work. I feel like it is because I shouldn't have put it so close to the floor. I tried to use the Position Property, it didn't work. When I attempted to use :MoveTo on the player's humanoid, it failed miserably as they weren't even running. I tried to edit the WalkSpeed and it still didn't work. I linked parts together. This was made on the Server Side, on Roblox Studio playtesting. There are no errors as much as I can remember. This was attempted over 9 times. Unluckily, I lost the script. I really need help with this. Thank you very much for reading.