Hi,
Thank you for posting in Symantec community.
There are few tasks that you must do on Windows operating systems to successfully install the client remotely. I would suggest to check pre-requisites on those new PC's prior to install SEP remotely.
Preparing Windows and Mac computers for remote deployment
http://www.symantec.com/docs/HOWTO81300
Steps to prepare computers to install Symantec Endpoint Protection 12.1.x client
http://www.symantec.com/docs/TECH163112
About client installation methods
http://www.symantec.com/docs/HOWTO81302