Deactivation of SDL Trados Studio 2015 Freelance Plus on old computer and activation on new computer

I have bought a new computer and want to deactivate my license on the old computer and activate it on the new. I have tried clicking on "Deactivate" on the old computer, but the license still show "in use" under my account. I have closed and reopened my Freelance account several times and clicked on "Deactivate". I then get an error message "Deactivation failed. Could not revoke this license. Revocation is either complete or revocation proof is already uploaded.

I also tried the "Deactivate offline" option and received an email with a deactivation authorization ticket, but the program will not let me copy and paste the code into the dialog box.