hmm I have seen this when normals sometimes gets locked. Try going to polygon menu > normals > unlock normals.
it can also happen if you have additional poly nodes *usually a side effect of working in polygon proxy mode). In this case you have to go into the hypergraph and separate the smoothed and unsmoothed mesh.
You might try mesh > cleanup to ensure you do not have laminate faces or some kind of non-manifold geometry.
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675
Last edited by ctbram; 01-02-2012 at 07:01 AM.