Thats easy to fix. Make sure land ownership is the right way. If they are walking on your property before entering the main gate, they do that. That only happens from trainers. It isn't as bad as what happend to me once. I built a whole map-wide park, and opened it. Guests walked up to the gate, (even though it was free) and turned around! I looked close, and somehow the trainer raised the gate about 2 pixels, just enough for the guests to think it's the end of the path.
A word of advice: read CrystalKat's post.
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Intamin: Steel gifts from the gods.
CCI: Wooden gifts from the gods.