HaloMods "Classic" Read-only Archive

well i downloaded other peoples ppf files and modded the maps using them and it worked then. It only doenst work when i try to mod the maps

I softmodded my xbox, took the new maps off the harddrive. I have been trying to use dothalo and after i make my changes, I fix the encryption. Then, i resign the map file and overwrite the original file on my xbox. It always says map failed to load. I have tried everything. Any help is appreciated.