Can't Upload world to Server

When I attempt to upload a world, The progress bar goes all the way through, and it looks like it's completed, but when I try and log in it is just a generic world, and not the one I tried to upload. I have renamed the world to "world", i've made sure the version is right, the map works in singleplayer, I don't know what else to try. I've tried uploading from firefox and chrome, no difference.