I found an amazing item while reading through the manual for my Canon Flash. There's a footnote that says:
< If the flash exposure confirmation lamp does not light, move closer to the subject and take the picture again. You can also increase the camera's ISO speed.
Seems Canon thinks that if you are using a recent flash you are going to be using it on a digital camera. In the film days, in order to increase your ISO you had to switch rolls of film.