[Server Not Starting]

Everytime I try to start my server it says starting... then it goes to offline. I really need a fix to this asap

[Void World]

I'm Trying to make a Box PvP server in the sky but making a void world wont work for me. I've tried 

/mv create <WorldName> normal -g VoidWorld and stuff like that but it won't work anyone know how to fix this and get a void world?