Normaly this should be in the WinRar installed folder. %program files%\WinRar type of thing. as the key needs to be in the main path where the exe launcher is. Have you tried to force the file into the VOS winrar folder? Without updating your pack (Also make sure if it's windows 7 to actualy give the rights to copy the file)
Also make sure it's the right version for your .key file as some programs need to have the correct version or have it updated on WinRar's website should your product key need updating.
The only other issue I might see is if the WinRar key is machine id coded your Cameyo pack will be useless on another machine but if your using it on the same computer then it shouldn't affect your building of the pack.
