The message indicates you are trying to run the diagnostic tool on an offline remote computer. It will only have diagnostic results when the remote computer is online.
If the remote computer is showing as offline and you receive this message, please check the remote computer to make sure it is on, awake (Unless remote wake has been configured), connected to the internet, and has Splashtop Streamer running and logged in to your Splashtop team.
Please run the tool on an online computer from the computer list.