Remote Assistance is NOT Remote Desktop. Windows 7 Home editions do not support Remote Desktop INCOMING connections. You have two choices: Use a third party application/service such as LogMeIn, GoToMyPC, VNC, PCAnywhere, etc OR upgrade to Windows 7 Pro or Ultimate on the machine you want to connect TO.
Quoting:
Remote Desktop and Remote Assistance use the same underlying technology, but there are differences between these features.
• Remote Desktop allows access to a remote Windows computer. For example, when you are at another computer you can use Remote Desktop to connect to your work computer from home and have access to files and applications.
• Remote Assistance allows a helper to use an Internet connection to access your computer to provide assistance. The helper views your computer's screen and communicates through a chat box. The helper can remotely control your computer to resolve a problem.
The above quote is from the last question on this page:
https://www.microsoft.com/windowsxp/using/helpandsupport/rafaq-general.mspx