Dell XPS 10 keyboard doesn't charge

For the Dell XPS 10, there seems to be a problem with the keyboard just purchased. It doesn't seem to charge, even when the computer is saying it's plugged in and charging (but stays at 10%). I've updated the computer, etc and still no joy. It does charge the tablet when it's docked, but not the keyboard.

When I plug in the charger, the charging light comes on on the keyboard, but doesn't charge.

Windows shows battery 1 being charged and increasing percentage, but it shows battery 2 as charging but remaining at 0%

The keyboard is a USA layout.