Hi,
Thank you for posting in Symantec community.
Add this article to your favourite list, it can give the info about SEP system requirements, release notes & fix notes.
Release Notes and System Requirements for all versions of Symantec Endpoint Protection and Symantec Network Access Control
http://www.symantec.com/docs/TECH163829
Try with the latest SEP version (12.1 RU3) and check if you get success.
In case no success then please share the error screenshot.