I'd really like some help on this little issue that I'm having with when I try to teleport a minecart to another area.

I have a track and at the end of the track I have a detector rail connected to a command block with the teleport command set up to teleport me into a 10x10 or so square about 20 blocks away. Whenever I get into the minecart and come close to the detector rail it bugs out. It sort of teleports me very quickly but in a short moment I'm back where I was.

Any help on this? Thanks guys.