I had the same problem on an Asus eeePC X101CH. There was no sound from the speaker, even with volume at 100%.
A partial solution is to change the channel being controlled to Headphone. In the panel, right-click the volume control and click Preferences. It's only a partial solution because Lite always starts with the sound level at 0. You can easily turn up the volume, but if you plug in headphones and then unplug them, the volume control once again returns to zero.
A partial solution is to change the channel being controlled to Headphone. In the panel, right-click the volume control and click Preferences. It's only a partial solution because Lite always starts with the sound level at 0. You can easily turn up the volume, but if you plug in headphones and then unplug them, the volume control once again returns to zero.