re charging

I have threedifferent wall plug chargers all show output at 5volt dc at 0.45A. I also have 2 Clip + 4GB players and the latest model.

When I try to recharge on any of the wallplug chargers they will not take any charge, The battery symbol does not indicate charge either.

If I charge through a USB port on my computer they take the charge and indicate the flow on the battery symbol.

Is there anything that I can do to change this? wall chargers being more accessible than computers.

Do the wall chargers work with any other device you have? Maybe they’ve bitten the dust. They do tend to fail or simply stop working without notice and/or when you need them the most.