Knee rig help

I am doing the BSoD intro to character animation and am stuck at the knee part. the directions say to
semmetrically extrude the bone from root of the upper leg bone
name it knee
disconnect the bone (Click con off)
Make the bone the child of the master
then it says to move the knee away form the other bones but when I try the bone is still stuck and moves the whole leg. am I doing something wrong or missing something???
can anyone explane how this is done corectly?? it would be much apricated.

You need to disconnect/unparent the corresponding (L or R) bone also . You can use the Alt-P shortcut to disconnect/unparent as well as using the armature bones panel . If you don’t do it to both the X-Mirror will move the bones on the side where you disconnected the bone as though they are still connected .

Yes! thank you so much Vertex Pusher that did the trick. now on with the tut.