ImageMagick 6.3.6 has problems importing GrayLevel SCT files.
It tries to import them as RGB and reaches the end of file since it runs out of data.
Here's an example file that fails to import:
http://members.wolfram.com/flavios/magick/parthenon.sct
Thanks
GrayLevel SCT files are incorrectly imported
Re: GrayLevel SCT files are incorrectly imported
Fixed in ImageMagick 6.3.7-0 Beta. Thanks for the problem report.