"The license server rejects it", meaning my activation code

I had to replace a 2 yr-old Macbook Pro with a new one. After updating to El Capitan yesterday, then using Migration Assistant to move my apps and documents to the new machine, I launched Paralles and was told to update to the latest version. Once I performed that task, I was given the Activation screen. After retrieving my code from my account page, I entered it, saw the green checkbox, and clicked "Activate". I now see an alert that says "Unable to perform the operation. The license server rejects it. Contact the Parallels support team for assistance."

If someone from Parallels support is listening, please help.

Thanks!

--Bill