Perhaps not help, but I have some ideas.
1. Do you have a purchased copy of the game wtih all updates? The CK and the Game must be the same version for mods made with your version of the CK to load in the game version you have.
2. The CK also needs to have rights to write files to your game directory. Using the Steam folders resolves that, what folders are you using? They also both need to be installed in the same location with correct registry entries. The game will only load plugins saved to its Data folder.