Ard,
You have my sympathy. This is why I almost never use flash. I've been photographing for over 50 years and any time I try to use a flash I forget something basic. Having (finally) mastered the point Howie just made, I recently tried using the built-in flash in my P&S at a concert, and,of course, got clear pictures of the people in the row ahead of me but pretty much black on the stage.
If I had thought, I would have realized that there was no way this dinky flash would reach to the stage.
As one of the other L-L posters (I forget who) quotes in his sig-block (from the Three Stooges, I think?): "I keep trying to think, but nothing happens!"
Or, as Homer Simpson syas, "Doh!"