new computer doesn't recognize license

[Cathy Evers 0]

I have a new PC; used Activation help on Nitro site and entered serial number when asked and then this came up: 

Once you click “Deactivate”, you can activate your license immediately by entering the below serial number into Nitro Pro.

And then we hit deactivate and it says, "you may only deactivate 0 devices" and I'm going round and round with zero results. 

[AllainU 0]

Hello @Cathy Evers,

Thank you for reaching out to us through our Community Forums!

In order to further assist you, could you please provide the serial number of your Nitro Pro?

To send it via private message, hover your mouse on top of my name 'AllainU' and select 'Message'.

Thank you very much in advance and I am looking forward to hearing back from you.