When registering the ATP appliance, you are asked to upload the license file. After selecting the file, you see:
Error uploading license
This indicates a communication issue when trying to upload the file to our licensing servers.
Verify that the ATP appliance has access to the licensing servers; the Cynic license server [https://licensing.dmas.symantec.com] and the Aztec server [https://register.brightmail.com] by using the 'status_check' command at the console.