I'm trying to pan-sharpen an area of color 4 band 1m resolution NAIP imagery with a smaller area of 60cm 1 band grayscale imagery. I get an error of "No valid colors found within the specified area..." for the NAIP image. What does this mean and what is wrong? It's a 4 band color image and when I click on a pixel with the Feature Info tool I see 4 "valid" bands (colors) and their respective values. How do I do anything about this error?