Error Code 3600:0749 - Invalid AC Adapter Detected

When one of my Latitude E6500 laptops boots, I'm getting this error message.  The power supply is the correct one, but we purchased a new one from Dell just to be sure.  We are still getting this error message.

I ran the extended diagnostics, and everything else passes except for this.  I would appreciate any ideals on how to correct the problem.

Thsnks