This post on the Apple forum seems to answer this question. It is not a permanent fix, but it might help.
https://discussions.apple.com/thread/1365569?start=0&tstart=0
I am having the same problem but I'm wondering if replacing the keyboard solves it. Also, the instructions on this site don't refer specifically to the ribbon cable.
In addition, in trying to fix the ribbon cable, I had the small ribbon cable on the opposite side in these pictures fall off. I don't know what it does and it doesn't seem to have affected anything but I also don't know how to get it back on. Any suggestions?