The file containing the icons (
units_32.pcx) you are using is apparently not large enough to support more than 168 icons (12rows x 14icons).
Are you using the original
units_32.pcx for Conquest or did you make your own using a PTW(or one from a mod) version of this file? PTW version of
units_32.pcx is as it happens exactly 12x14=168 icons large.
Vanilla version of
units_32.pcx is only 6x14=84 icons large btw - jfyi.
Hope that fixes it