Red-eye even WITH an external flash...wtf?

[996GT2]

I was shooting an event for the school newspaper today. Had my 40D, 55-250 IS, and 580 EX. Due to the layout and lighting of the room (poor lighting, glass walls, and high concrete ceilings), bounce flash was out of the question, and so was using high ISO alone without flash. So, I had to resort to using direct flash with my 580EX. However, I noticed that I got red-eye in about 1/2 of my flash photos. I didn't have FEC set to a very high amount (I had it set to 0 for most of my direct flash shots).

I've read on the internet and in photography books that one of the main advantages of using an external flash was to eliminate red-eye, since the flash is much farther from the lens. So why am I still getting red-eye even with the 580EX?

 

[Flipped Gazelle]

The low light levels of the room cause greater dilation of the pupils, which in turn increases the chance of red-eye. Also, I wonder if the reflection of the flash's light off of the glass walls was at the proper axis to cause red-eye.

Were the red-eye "victims" really fair-skinned with pale blue eyes? Those are most susceptible.

 

[corkyg]

It can also happen when the subject looks directly at the flash