Hello, I have a Savi 8240 - it has a spare battery charge compartment. When I put the spare battery in there the light blinks and will not turn solid green. When I put the battery in the headset it is not charged. I have tried to charge both batteries on the "cradle" charge while they are inserted in the headset and they both hold a charge when inserted in the headset and in the cradle. The spare battery doesn't appear to be charging while in the spare battery compartment. Any solutions to this?