My creation won't save.

[CreatAr]

Hello there, my problem is that after i create something in the level editor and save it, it wont be there afterwards. Even if i save it a hundred times, won't work. I've followed guides on youtube and done all the pre-scripting needed to make a level, and i even made one. But only basic one with floor, starting position and some light. That one worked to save but not anymore.
Please help, and thanks.