If a fast root cause and fix to why a push install/update does not work OR cannot be used due to the site policy follow the next steps:
1. Uninstall Veritas Backup Exec Remote Agent for Windows from Programs and Features.
2. Manually install Veritas Backup Exec Remote Agent for Windows.
Refer Article: 100008039 for manual installation.
Note: Depending on the Windows Operating System and Microsoft Windows Installer request(s), the uninstall or install of the Remote Agent may prompt for a reboot of the server.