Hello, I NEED HELP!!!

"I am fairly basic with modding Halo 2. I have modded all of the new maps and I have copied the old maps onto my HD. But one thing I don't know how to do is how to mod the campign maps and put them onto my HD so I can play them with mods. I have treid it before by opening up the campiagn maps in DotHalo and editing the weap and Bipd tag and so on so fourth. After I am done editing I hit fix encyrption and resign the maps and put them in my Halo2 folder in E://Games/Halo2. When i load the Game from the HD (not the disk) I go to the maps that i edited and it tells me the disk is dirty or damaged and so I can't play them..............HOW DO I MAKE IT SO THAT I CAN PLAY ON THEM WITH THE MODS?????????"

And for the second time i don't think it is because of my disk. My disk is brand new.
Is there a different way to resign them or something?