I have a Canon rebel and bought a Focus external flash for it. When I have it set to ETTL, the pictures come out really dark. It's like it's thinking that since there is a flash, the camera is adjusting to compensate and the exposure isn't enough. Doesn't matter if I make the exposure length really slow.
The other problem is that if I put my flash in manual mode, it won't even fire even though it's still attached to the camera.