the moment you put any outside pressure on the legs that turn the knee, you can be DQ'd for reaping the knee. Also Knee locks are prohibited from blue belt and below as far as I'm aware. I know that the Lockdown doesn't reap the knee but I did it in my last gym and was told by the coach that it would be illegal if I tried it in a competition and I would have been DQ'd. He's a regular referee, Judge and very highly regarded around here.