[JoeF]

I think that for the reasons nightshade gives, bat photography is seriously discouraged.

Basically, your camera is too advanced for the job. You need a manual camera where you set the focus prior to taking the picture. Then when you push the button the flash and shutter fire immediately. If using film, go for iso 100-200 for better resolution rather than the higher speeds as the flash is doing the work, not the ambient light. You could also play around with longish shutter speeds to get some background colour and give a sense of movement. Thats how I would approach it but bear in mind, there is always some pot luck involved with taking pics like this.

Joe