I figured this has been discussed before but could not find it. Anyway, I have a Rebel XT and a 580EX II plus a Promaster 7500DX.When using these flashes off camera on a bracket with the canon off camera cord I may get sometimes 10 or more flashes and then the flash indicator light is no longer in the viewfinder,the flash still fires but the image is totally dark. I have to take the flash off the bracket, put it back on and then it will start working again maybe for 30 or more flashes..sometimes only 5 before messing up again. Very unnerving to do a wedding and you have no idea when your flash will fail. Both the 580ex II and promaster flashes are doing this. Camera and flash contacts are clean and pins are fine. Flashes started doing this right out of the box. On another forum 2 more photographers posted a message on this same problem with their 30D\'s. Then another one said he has had the same problem with his 1D and speedlite flash, not the 580ex for 2 years now. Canon is no help on this matter of course. Does anyone have any idea the solution to this besides selling the ettl equipment and using auto flashes? My vivitar 283 and Promaster 5950 in auto mode do not do this, they fire everytime and every image is great..is this a problem with ettl II? Last night I shot 10 images of the same subject, letting the flashes fully charge between shootings and on #8 the flash indicator was no longer in the view finder and image was totally dark and yet the flash fired.Solution please?