AC Adapter for Charging Sansa Clip w/o Connecting to Computer

I bought an A/C wall charger on Ebay that had a reported 5 VDC/ 500ma output but it would not work with my 2GB Sansa Clip.  The charger works good with my Sansa E270 player.  The Clip charges OK using the USB port on my PC.  When using the usb port on the PC the Clip’s charging light blinks.  When I use the A/C wall adapter it does not blink or charge ??

Does anyone know if the charging light should blink when using a wall adapter???

/jds