Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
I confirm we get only 64 shades, and I don't know why. I'm looking into it.
However, note that your "-remap palette.png -dither FloydSteinberg" is wrong. "-dither" is a setting that is used by "-remap", so should come before it, not after.