Unable to reactivate subscription for another device

Good Day,

I purchased an AVG subscription for up to 10 devices and successfully reactivated my own subscription, but I'm unable to reactivate the subscription for another device. Every time I type in the license number, it says its invalid. Please advise.

Hello Lauren,

We are sorry for the inconvenience caused. 
May I know on which device you are experiencing the issue?
To get the screenshot of error message, we have sent an email.
Please revert to our email with the requested screenshot.
Thank you.