Okay firstly, can you post some images of what you are doing, we cant see the book cheers Jay Oops, sorry, Jay. I forgot to attached the images. Now I attached the images. I'm doing the spine IK rig tutorial in the book. (see attachment book_01, 02) When I finished "adding a stretchness switch", I noticed that the my spine chain looked like this. (attachment joints_b) It was originally like this. (attachment joints_a) What happened was that when I changed the "second term option" of the condition node "StretchCond" (see attachment hyp_sha)from 0 to 1, the joint3 and 4 overlapped andn thus, the whole chain got shorter, as you could see. Chain structure itself is pretty simple as you know. (see attachment grh_ed) I just can't find what I did wrong to cause this problem. If you could point out, I'd really appreciate that. Thank you. -naoki