I am operating Yosemite on my IMac and have a HP 6600 printer, scanner, fax connected to it by a USP connection. The printer works fine most of the time but when I want to scan something I usually have to delete the printer and then add it again. Now I am trying to scan a page and after opening the scanner, selecting the feed (glass or feeder) the scan button won't light up for me to select it. I have deleted and re-added the HP device twice now but the scan button looks like it is still not highlighted for me select it. I have gone to the HP website and downloaded the software for this printer and installed the software successfully. I am able to bring up a document and print it fine, just can't scan. Any suggestions???