Instrument Panel Light out?

[ApolloX]

I havea 2007 4-door Yaris. The other night I was driving and I noticed if I turn my light panel dial (shown below) all the way up, the RPM/MPG dashboard items go completely black. The clock stays visible.

http://www.selikoff.net/light-panel.gif

First off, am I correct in assuming this is a problem? I thought turning the dial all the way up, put it at maximum illumination, but I could be wrong.

Second, are their two lights involved? The dashboard is visible at non-maximum illumination, but non-visible at max. This would sort of make sense if there were two lights involved and it was flipping between the two at max. Is this correct?

Finally, am I looking at a fuse issue, a lightbulb issue, or an electrical problem? Any tips?

[BLH]

If you turn it all the way up until it clicks. Some lights go back off.
I usually have mine up to just before it clicks.

[bankrobber]

When you push all the way up it is supposed to be brighter. I use mine when raining and I need to turn on headlights. If I wear sunglasses I can see display unless I turn it till it clicks. I would guess it is all one bulb.