in particular the /codebase flag is important. You can only install a dll to GAC if its strong named and .net wont be able to find it if its not unless you use the codebase flag.
I had to manually figure out the missing keys by comparing the registry of a machine i compiled the dll on vrs just using regasm yuk..easy to find once you know the problem. Hindsight is 20/20..
Also make sure to pay attention to the 32 bit and 64 bit thing..