i had a canon xt and bought a sigma ef 530 dg super flash. and had no issues. i just purchased a canon 40d and when i hook the flash up it fires on the first shot. but when it recharges the flash does not fire on subsequent shots. i tried all the different modes and still have the same problem. i checked the camera settings and tried them several different ways with no result. these tests were done useing a zoom lens. i also tried M, av, and auto mode with no luck. what am i missing here. is there a button on the camera i need to hit? please help.
