Need more information but this can happen for many reasons.
Here are couple to look at
* You have more than one color selected on the color wash effect and it's changing colors
* The morph button is selected
* You're looking at the palette of effect 2, but the effect selected is effect 1
This one get's me often if I'm not paying attention.
* Your model is not set up properly and instead of 123, 456, 789, it starts at 234, 567
What ch# does your pixel tree start on?