Hello, My main goal when buying the Yongnuo system was to be able to use my flashes wirelessly in High-Speed Sync. Hopefully someone can guide me in the right direction. What I'm working with: - Cannon Rebel XT - Cannon 580EX II - Cannon 430EX II - Yongnuo 622C Flash Controller - 2 x Yongnuo 622C II Tranceiver The Problem: - I am able to get the 580EX II to fire, but unable to control the flash with the controller. - The 580EX II does periodically switch from ETTL to TTL, but I haven't noticed it happen while trying to trigger the 580EX II wirelessly. I'm not sure if that has anything to do with my problem. - I am able to control and trigger the 430EX II with the Youngnuo system without any problems. I just don't understand what's going on with the 580EX II. Thank you for taking the time to read this post and any knowledge that will help enlighten me and others on this situation.