Greetings, I am unable to change the color class of some photos when using Photo Mechanic 4.6.6 (on a Mac running Snow Leopard).  These photos are older photos that I color classified with an earlier version of Photo Mechanic, probably over a year ago.  Today, using 4.6.6, I can change color classes of previously unclassified photos with no problem.  Is there any way to remove the color class from these older photos so that I can select a new one?  Thanks in advance for any assistance.