AnimationAnnie

I am VERY new to creating animations. I am hoping some experienced animatiors can help me. I have been unsuccessful in searching for fixes or tutorials that adequately cover this type of movement. Using DAZ Studio 4.6 - The desired action: character is kneeling on the floor sitting back, on her knees, butt moving up and down as part of a dance move. In DAZ, I pin the feet and hands to the floor, use the translate to raise the butt up and down through several key frames. The character moves correctly, knees flex, shins flat on the floor, as her butt rises slightly then back down in the editor.. BUT.. when I upload to SL, the knees don't bend and instead the whole avatar floats hovering up and down in space like she's bobbing on a raft in waves. Why does the action show correctly in DAZ, legs fixed on the floor butt moving up and down but totally opposite when uploaded to SL, bobbing up and down in space? Does pinning not work in DAZ? Is there some other editor I should be using to achieve this action? Tried SLAT but it seems to crash on my 64-bit system Expert or experienced advice appreciated.