The wrong user was being targeted by the destination teleportation.

This bug was specifically added in version 0.5.0 as it was swapping over from using server based uuid's. If your server is setup with ip forwarding and each of your underlying server set up correctly for it then this should not effect you if you have 0.4.0.

Sorry for any inconveniences caused. I have archived these versions on bukkit to stop any further issues from people downloading these bugged versions.

If the version is not available on bukkit yet you can get it from github
https://github.com/sekwah41/Advanced-Portals/releases/tag/0.5.2