Windows Upgrade Won't Work

I have bought a new computer and it had Windows 10 Home installed. I purchased Windows 10 Pro and had it installed on my last computer but when I put the key into the upgrade it tells me it can't do it and I should click 'Troubleshoot below' but there is no Troubleshoot link. Could someone tell me what is probably happening (or not happening)?

See these links:

https://support.microsoft.com/en-us/...-10-activation

https://support.microsoft.com/en-us/...ng-home-to-pro

https://support.microsoft.com/en-us/...ivation-errors

https://support.microsoft.com/en-us/...troubleshooter

Will do - thanks