Minecraft Modded Server

I'm trying to make a modded server for my friends and I to pay on. It's up and running but I try to join the server and it's stuck on the screen. It just says "logging in…" and on the server logs it says " Netty IO #2" "Unexpected packet during modded negotiation - assuming vanilla or keepalives" Anyone know how to fix this?

Added (1). Also says something about "Handle is invalid"

Can you post your server log to http://pastebin.com/

It could be numerous things, mods not supported for that version, using wrong forge/minecraft version, can't say without seeing the log.