By default, a system administrator must be logged on to the computer that the program will be installed upon.

The Allow admin to install from Terminal Services session Group Policy, at Computer Configuration\Administrative Templates\Windows Components\Windows Installer, creates an exception for computers running Terminal Services.

If the policy is Not configured, you can enable this functionality by setting the EnableAdminTSRemote value name, a REG_DWORD data type, to 1, at HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Installer.