License Key "Invalid"? How can THAT Be?

I am a licensed user (obviously) and shifted my main computer to a new desktop, then reinstalled SmartFTP and when I tried to use "Help/Enter License Key" and pointed it at my license, it said the license key was "invalid" - how do I install SmartFTP on this second computer? Please advise as soon as possible as I am trying to update my webssite! Thanks.

JLP

Please contact us over the support email address and include your license key number and other details.

Thank you.