Help! - my digital bare bulb won't fire!

Hi, I wonder if anyone could help me with a lighting query...?
I am finding that my digital bare bulb does not always fire when my master flash fires. I have tried re-positioning it (as the bare bulb is tripod mounted), but there seems to be no rhyme or reason to when it chooses to fire. I know that the barebulb needs to be in line of sight, which I am always careful to ensure, but I still seem to get inconsistent results. Can anyone offer any insight/advice?
Many thanks,
Emily
(Canon EOS 30D and hot shoe mounted flash gun)

I don't understand what you mean by "digital bare bulb." What brand and model of flash are you trying to fire and what are you trying to fire it with? Are you indoors or outdoors? Is it dark or light where you are working? "Canon EOS 30D and hot shoe mounted flash gun" in your signature doesn't tell us much either except for the 30D part.