I find 2 clients of my SAV Server(Version 10.1.5) is missed their scan engine from SSC, and reinstall the SAV client was still not working. But I had solved the issue and the steps is as follows:

1, uninstall the Symantec AntiVirus.

2, delete the folders of
%SYSTEMDRIVE%\Program Files\Symantec,
%CommonProgramFiles%\Symantec Shared,
and "Symantec AntiVirus" in the Symantec AntiVirus install path.

3, install the Symantec AntiVirus again.