Ring Video Doorbel Generation 2 not charging from solar panel

I purchased the Ring Video Doorbell Gen 2 only a couple of months ago and followed that up with purcashing the solar charger when it recently became available.The Doorbell lasts approx 48 hours with a full charge with all motion detection turned off, I made sure the solar charger was in full sun for 2 days before conencting the doorbell. Unfortuantely it made no difference to the amount of time the Doorbell remains charged.I tested the power output by conenctign another micro USB device and confirmed there is power output from the solar panel but it simply offers no charge whatsoever to the Doorbell.Cheers