I have a Canon ix6520.  For some reason, the printer all of a sudden no longer recognizes the magenta cartridges.  There's plenty of ink.  Of course, she won't print because she thinks the cartridge is empty.  Help please.

Nevermind.  I would say tempermental old *@!#*, but sh'es only 2

When my Epson does that, I take all  the cartridges out and wipe the contacts on the cartridges and the printer with a paper towel that has been dipped in airbrush cleaner(alcohol) ...works every time!