I used my 5D (original 12.8mp body) and Yongnuo ST-E2 and 420 and 430EX's off camera for a lot of my work involving flash. I recently replaced the 5D with a 6D. I tried using the 6D and Yongnuo ST-E2 for some off camera flash work and every picture at every setting is terribly underexposed. I even dialed in +3.0 flash exposure and +5.0 compensation and slow shutter speeds trying to get an image that wasn't underexposed. To make sure my ST-E2 was in good working order I grabbed my 15 year old 1Ds and a couple of Speedlites and everything worked perfectly. Any idea what the problem might be? To make sure the Speedlite's weren't the problem I tried them on the 6D and didn't have any issues.Could the problem be that the Yougnuo ST-E2 is not communicating with my 6D?