Some advice on lighting for event photography

It's been awhile since I synchronized flash with ambient light manually, but I seem to remember that the shutter speed controls the exposure for the ambient light. The key to event photography lighting is balancing the subject lighting with background lighting. If you use a large aperture and slower shutter speed the subject will be well lit and background will have more detail. Chose a higher ISO, I used 400 to shoot inside churches. Avoid direct flash and use a defuser. For my set up, I used a Nikon D80 with an SB800 flash, I mounted my flash on a stroboframe bracket so the flash is always above the lens, this minimizes flash shadows. You can set the camera to ttl. I always get good results shooting about F4 30th. Without seeing the shots it is hard to advise you but I hope this helps. While I've found flash metering to be bit more reliable and a convenience if your subject is always changing distance from your lights, you need to at least meter ambient and set a manual exposure if you want usable results. Also I would try lengthening my shutter speed a stop to increase the background exposure.