Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
The resulting TIFF image is fine, its just that there are very few TIFF readers that handle the full gamut of TIFF image types. In your case you will want to reduce the image depth from 16 to 8. Add -depth 8 to your command line.