The reason why it does not work, is because the realtek driver and app use in most cases auto sensing.
But if you are using windows 7 it has a battle with it.
If you right click on the speaker icon of windows next to the time, and select playback devices.
It will list all of the audio output devices, where it says HD audio device have a check to see if it is set as the default audio playback device.
You can do this by right clicking on the device listed. and selecting default device.
If you are presented with headphones, then it must be right clicked and set as a default device. so the headphones work when plugged into the 1.5mm jack of the laptop.
If you find everything is grayed out, in windows sound manager then the Realtek sound app must be uninstalled, to allow windows to use the audio options.
It is a common problem between the realtek app managing sound. and the way windows 7 uses audio devices, and its routing.