IK Chains animation

I'm the new guy here, and might got into the wrong thread, but anywayes. I'm trying to animate the IK chain in 3DS Max. I'm using the HI solver, btw. The chain itself moves, but the bones don't follow it. It just takes the right pose in the last key frame. The worst part is, that it actually works properly sometimes, and sometimes, most times, don't, and I can't figure out what effects it, and why sometimes, it works like I want it to, and sometimes I see only chain move and bones 'jumping' into the right location on the las keyframe!