I know this doesn't help YOU in the situation you are in presently, but I've got to point out that you don't recommend them to anyone, but that link you gave has mounting instructions for it, and seem pretty easy to figure out how to mount.
Is there something that the mounting instructions on that link DON'T tell us that your personal experience would refute? They seem pretty easy to mount - to me, anyway - and your experience seems as if there was something missing or you couldn't follow the instructions.
Not a slam, but it'd be nice to know - in case your experience is just out of the ordinary. That's all.