I watch the tutorial. And youre right, Ik tracking works fine with legs. I think one of the problem is the type of constrain I have to use in each bone. For an example: the knees. Its a ball joint? How much degrees each part can bend?
I remember read a tutorial, some years ago, with all the bones of a basic 3D skeleton and his constrains. If I find it again...!
Thank you again, Sardtok!