It's means NPE version does nt support windows Server OS
You can scan SymHelp
How to run the Threat Analysis Scan in Symantec Help (SymHelp)
Edit
System Requirements:
Microsoft Windows XP with Service Pack 2 or 3, Windows Vista, or Windows 7
Your computer must support USB booting for the Norton Bootable Recovery Tool to run on a USB device
https://security.symantec.com/nbrt/npe.aspx