Minecraft Xbox 360 Bug (Horizon won't accept savegame.dat)

Alright. I am trying to load in a “savegame.dat” file into Horizon so I can put it on my Xbox 360. But it won’t let me put in the world. It says “Invalid STFS Package”. Is there a way to fix this?
I would dearly respect any help.

Besh Wishes,

Replace the .dat file in a existing save with the one you downloaded.

How do you do that?

Transfare a save for the game from your xbox and edit the contents.