Ok, here's the solution to a colored cell in a grid based on a color value in a field. Putting the field reference in DynamicBackColor doesn't work (i.e., "mytable.ccolor") however if you put in a conditional statement
="iif( empty( mytable.ccolor ), rgb( 0, 0, 0), mytable.ccolor )"
it works. Don't know why, but it works.