Why is the headphones not charging

I think you have the lights mixed up. Green means the base unit is plugged in to the mains and transmitting a signal. It should come on when you first plug it in and stay on as long as there is an audio signal fed to the unit. It goes off after a few minutes of silence to save power and spectrum.

The red light comes on when the headphones are sitting on the base and being charged. If it doesn't come on, check for dirty contacts betwen the headphones and base unit and loose batteries.