Screenshots let people get a feel for your work, and is the most important part of a node. They should be the correct size, and have no heads up display elements. Refer to the User's Guide for information on how to fix this.
The site maintains a strict policy of only having content that is of value to the public in some way. Content should be thoroughly worked on before submission, and a node will be unpublished if something remains seriously wrong with it for a long period of time.
If this is a map, it could mean a problem with the lighting, texturing, geometry, or layout; try the Cube Wiki for tips on using the engine. Should it be some other form of content, then it may need to be elaborated upon to be worth something.
The layout of a map is among the most important parts of a winning design, try making sure exotic geometry is removed or clipped and the level is open and free of dead-ends or unexplained phenomena.
