Cant join on server

[CallMeYuuuu]

Hay, I have a problem with the joining in Minecraft. I can start the Server and it loads also all plugins and worlds, but wehn i want to join on it in Minecraft it say: "No conection to the Server" but i am conected and i can join but even when i have conected i only see the ingame screen for less as a second. Pleas help and sry for my english i know its not the best. :/