Howdy,
It’s difficult to tell what the problem is without an example file to load into Cinema 4D.
But typically, it’s not a good idea to try to constrain IK’d joints. The IK and then constraints then fight each other for control of the joints.
Adios,
Cactus Dan
Cinema 4D R13 Prime
http://www.cactus3d.com
http://www.cactus3d.com/Plugins.html