Thank you for your message.
Could you please clarify what Connection type
do you use when connecting to the remote machine via the Remote Install Tool? In case if you use Remote Utilities security, please try using the Windows NT security
instead, as it allows you to connect to a remote computer using admin$ share.
In addition, please note that since you've mentioned above that you're connecting to Agent
running on a remote machine, this might also be causing the issue as Agent runs as an application under the current Windows user without administrative privileges.
Please try restarting Agent as administrator first using the Restart Agent as
command and using the Remote Install Tool via Remote Utilities security (in case if you're connecting to the remote machine over the Internet) once again.
Hope that helps.