That script wasn't done by Autodesk, nor Discreet, nor Turbosquid, nor anyone of us here.  We are not the official support of all the custom made script/plugin done out there except those supplied with official game company's gamepack.

However, looking at your image, I can guess it is because your image might be too complex for the script. In other words, it might have too many polygons to work with.  Try the followin :

- add an Optimizer and play with its options
- then add an Edit Mesh
- select Polygon selection on that Edit Mesh
- select all faces
- clear all smoothing groups (smoothing group section of that Edit Mesh)
- click Autosmooth