Very strange, I would think it would work if there is DC present, but perhaps the Touch now requires a special authentication chip in the charger.
If you still have your old iPod video, would you be able to charge it with these DC adapters? If they can charge your old iPod but not your Touch, did they
ever work with your Touch, or is this a new Touch that you're just starting to use? Also, did you recently update the Touch's OS? Just curious if 4.0 could have enabled something that causes the Touch to look for an authentication chip.