Failing to unload the world

In my current plugin I want to unload and delete worlds.
But my Problem is that unloadWorld always returns false, even if the world was just created and no Player entered it. The world is not world,world_nether,world_end and there are no Players is it. Is there something else I have to do before unloading a World?

 

Giving your code, would maybe help

 

I donn't have a code yet. I just have been testing Ideas. I only have a command which executes:
Bukkit.getServer().unloadWorld("Gameworld", false); but it always returns false even if no Player is on the Server.

 

surely it would be "Gameworld", true? Not that i've ever done it just i'd assume it would be true

 

Now it sometimes returns true, but even after that, I cann't delete the Worldfiles because they are still in use?

edit: Or if that is not possible. Is there a way to completly regenerate a world with a different seed while the server is runnung?

 

I was struggling with same problem. Look at my thread:
http://forums.bukkit.org/threads/world-unloading.125193/

 

I Don't really know how you fill regionfiles and rafField with data about the World, could you please also give me your code for that.

 

https://github.com/KillerMinecraft/killer