From my palette importing guide:
The very first thing to know it that ZQuest organizes its colors first into CSets of 16 colors each. These CSets are then organized into 16 color palettes. If you have any questions about something I've said in this section, remember the difference between them (I've noticed some confusion in help topics between a palette and a CSet). The CSets are organized into rows, with 16 of them on each palette.
If only some people would bother to read things like this, we wouldn't have this problem. But they find the forums first, and most people prefer not to care if that guide's even there.