Hi,
The vs6555 is the front camera, the back camera is the omap3/et8ek8/ad5820/adp1.
Once you select the camera, you must also choose the channel (which is 'camera').. if you only select the device but don't select the channel, it will not switch from the currently selected device to the new selection.
Also note that with the current release firmware, the front facing camera shows very very dark images, so make sure you try putting a light bulb in front of it to see whether or not it works.