After the color ink cartridge was low , I refilled it in the first time and it worked very good . Last week, when I printed some pages with back ink, but some pages which had blue lines and I found out the color cartridge was low . I refilled it & checked , 3 color came out good shape , but when I printed , blue ( cyan ) NOT come out . I tried to remove all inks out of cartridge and refilled new one, but NO help . I do not know what wrong . Please help me out . ( I bough this HP Photosmart C 4650 on 1/2010 ) . Thanks . BT