flash exposures always different !?

[tikkeltokkel]

I have been taking pictures with my 10D and 550Ex at some night time fashion shows where the lighting is quite sufficient. My flash seems to need to be set at -1 1/3 or the flesh tones burn out. But from one exposure to the very next the pictures are worlds apart, and nothing had changed (same model same time and clothes... seconds apart.. i wish the canon flash system wasnt so dumb (maybe a Nikon flash technician should jump ship and help canon out of a flash system quagmire.) Any suggestions what i might be doing wrong?

[MrPogo]

Are the models walking along a catwalk? If so I'd imagine the distance they travel in those few seconds is what's causing the problem. Metering wise not much will have changed, but the model being that bit closer means the same strength flash gives different results.

[jcsorensen]

Are you allowing the flash to fully recharge each time?