Licence issue

Hey,
I want to install the license but I am unable to do so. It is the same machine I was trying to use the license. At first Mode solution was working but not FDTD, so I deactivated the license and installed both FDTD and mode solution. When I was trying to use the “activation code” after installation I got the following error message.

Please, help me to solve the issue.

As the error indicates:
"The activation code has already been used to activate your license"

The license was not deactivated properly or was not deactivated using the method outlined on our KB: