try usign a conversion node inbetween.... like a rgb to hsv... it sounds like the value is looking for a parameter that its cant decipher... the color channel is returning a vaule that is of type color (r,g,b,a value) and the reverse node is passing vector info back (or forward, X,Y,Z)... you need to put implement a node that will make the info correct for the renderer... either by connecting the out of the reverse into a hsv to rgb and then passing the rgb out to the rgb... or by passing the outColour att to a rgb to hsv and the out value att to the reverse... in which case the luminance variations of the combined colour attributes will be read as input values...
the verbosity setting you found is probably one of the great strenghts of MR... by default you should be using the progress messages setting... it will inform you of both prgress of the job... as well as describing ways you can refine the scene for speed...
r.
