Ankit,
When it comes to windows 7 installations you need to make sure that the agent is installed by an account that has Adminstrative rights. Windows 7 has MANY security features that has made it more difficult to install SW than it was with Windows XP.
So you need to configure the SCCM application to install the using an Admin user account. Also make it reboot the PC ust in case.
Make sure that you also copy the file to the laptop before running the installer. It will not work if you run the installer from a network attached storage.
Hope this makes sense.
If this solves your questions please marked as solved.
Ronak