Hi Moon,
Try this here:
Sample Video: MTV format for 1.8" screen player. It's an MTV video file, but thought I would get you to try it just in case your player doesn't actually play .AMV files at all!
Also, try downloading some sample videos for the Rockchip player (choose the "LARGE" section the Sample Videos download area).
Try the others and see what happens. Perhaps we're missing something and your player doesn't actually play AMV video files?