Not all deformation approaches works with the weightSplitting method (see my post about splitting weights with animCurves for details). Because the weightSplitter saves you so much time, it's often worth changing your rigging approach slightly so you can use it. One region of the face that is a great example of this is the lip roll. Every previous lip rig that I have worked with used on of three methods: The twist functionality of Maya's wire deformer. A joint per control tha