He has not enabled Remote Desktop on his Windows 8 computer.
The Remote Desktop Connection lets you connect your computer to another one over a network connection. You can enable Remote Desktop Connection via the Control Panel or Windows Settings. To enable Remote Desktop, click the System and Security on the Control Panel and click on Allow remote access option under system properties. A system properties dialog box will pop up and you will be able to navigate to the remote tab and check the radio button Allow remote connections to this computer. Click on Apply button to save changes .