If I created a new map, mapABC, could I have it be a clone of an already existing map, like Kashyyyk?

I watched a video on youtube that showed you can go into the "BF2_ModTools\assets\worlds" folder and grab the resources of any map, put them into a new map "BF2_ModTools\data_ABC\Worlds\ABC" and when you'd open it in ZeroEditor it would show the map and you could edit it any way you want and replace the original with it. But any time I tried using that as it's own new map, the game crashed.

I'm still very new to this but this seemed like a simple enough thing to do. Sorry if this is unclear, and thanks for any advice.