The Add-on I modified won't show in the World of Warcraft (WOW) Add on list if I change the name of the file.?

I modified an out of date add-on that someone else was modifying from an out of dateadd on. I need to rename the files so I am not completely ripping the guys work off. ID still give him gredit as the author and only credit myself with the revisions. My problem is this, every time I rename the files, the mod no longer shows on the WOW Add-on List when I boot up. For Example, the original file is called CRaziness.TOC,.I have modified the files Craziness.TOC refers to. IF I boot up like this, my modifications work fine (even the name changes on the add-on list),. If I change the name to MoreCraziness.TOC, the mod no longer appears in my addon list. CAn someone please help me?