metered manual mode

I have an mz60 which I'm learning to use. I'm finding if I use standard auto mode and get a shutter speed and aperture then switch to manual, it tells me it is way under exposed and I have to slow the shutter speed substantially to get my green circle.
In my night photography, other cameras were happily snapping away at f5.6 with 1/4 shutter speed and IS0 400. I started there and went to 45 seconds and it was still telling me it was under exposed (with or without the flash) I also tried telling the camera I had IS0 800 but that made no difference - do I have a fault with the camera or does the camera simply not take pics at night?