Hi , i have been trying to using this function call face dection on this 5d mk2 with wireless remote but it just wont focus unless the ( AF-on) button is press , i look through the manuel many time an cant find any solution to it but i tested it out on the 550d and it works so i was thinking is my set faulty or the wireless remote not compatible with the 5d .Any kind soul out there can help me on this , many THANKS in advance as this function does help in many ways in taking photo of my family during traving.