It is possible that it is a playback issue. When you play it back from the camera do the cam’s meters respond in a pattern you had expected? If so it might be recorded to a channel that is not being played back due to a cam setting. Always do a mike check from the cam’s headphone port or RTN in from the mixer and always play back some test footage at the location. If possible play it back on a monitor and speaker system rather than just the cam’s headphone output since cam’s HP amps usually suck.
Hopefully since you were using cheap equipment this was not for a lot of money. You might consider recording some interviews or a V.O. while the bride or whomever watches the edited visuals to use as a sound track. Or if these were interviews about the bride and groom you can always reshoot. Just admit to the bride that technical problems ruined the audio track.
MacPro4,1 2.66GHz 8 core 12gigs of ram. GPU: Nvidia Geoforce GT120 with Vram 512. OS X 10.6.x; Camcorders: Panasonic AG-HPX170, Sony Z7U, Canon HV30/40, Sony vx2000/PD170; FCP 6 certified; write professionally for a variety of media; teach video production in L.A.