If the license server refuses to serve the licenses, make sure you installed the license on the correct machine.
The license was activated for a different machine or activated using incorrect Host ID. Examine the Host ID recorded in the license with the Host ID for the machine. If they are mismatched, check-in and regenerate the license with the correct Host ID.
The license has been altered. Nothing in the license except some designated information can be altered. The license is rejected if you change other information. If the license is being created by typing from a paper copy, verify if there are any errors entering the license. You can also download a new copy of the activated license from SPDC.
If the Host ID for your platform is based on the Network adapter identification, verify that you have used an ID associated with a valid NIC. IDs associated with loopback adapters are not valid. If the ID associated with a removable network adapter was used, ensure that the adapter is attached to the computer.