I totally thank you for taking the time to answer my HELP question!!! I figured out after many hours of dealing with the situation that I had inadvertently checked the Preserve Luminosity box on a previous application of FILL. Then I was trying to fill a layer with nothing in the layer and nothing was happening. I thought there was a glitch in my program. Once the Preserve Luminosity box was unchecked everything worked properly.
Once again, your willingness to help a stranger is applauded!