QTR-Quadtone RIP

I'm beginning to get the hang of working with QTRgui, but I don't 
understand the "Advanced Adjustments" on the bottom of the screen.  It 
appears that there is a slider labeled "lightest" / "darkest."  But 
only the uppermost of the slider image appears...Maybe as a result of 
my monitor settings?  And there's a window reading "Not Monitoring."  I 
don't understand that.  Advice on the "Advanced Adjustments" options 
would be much appreciated.

Norm