When saving a map, data is lost.

Hey everyone! I need your help. I'm having this problem: I installed "Tribes of the East" version 3.0, and when I start making maps, everything seems fine. I save the map, but when I try to play it in the game, it's not there. Also, the size of any map I create is showing as 22MB. Here's another example: I downloaded a map, and it worked fine in the game. Then, I simply opened it in the editor, looked at it (without making any changes), and now it doesn't work in the game anymore; the map has completely disappeared from the game. Can someone explain what the problem is? Please help, and if possible, provide a detailed explanation with an example.