My DSLR has trouble shooting in the nighttime?

So I recently purchased the Nikon D3000 because i'm new to photography. I love taking scenery pictures, and i'd like to take some at night however my camera says it's too dark to shoot. If i take it with the flash, the pictures don't come out as good as well. Any tips?

1) ISO 100
2) shutter 30 secs+
3) aperture f/16+
4) NO FLASH!
5) tripod
6) PRACTICE!

Raise ISO but be ready for more grainy pictures.

It might be obvious but if you're shooting at night it will be a long exposure therefore you WILL need a tripod. There's no reason why your camera won't shoot at night you just need to find the right shutter speed. Keep going down until you get the right speed. But remember you will need the right aperture also. But if you set your camera to 'Shutter Priority' mode (should be 'S' on the camera) the camera should deal with the aperture, especially if you are new to photography.

Have your ISO set to either 400 or 800. This will lower the shutter speed but will increase the grain of the image. A lower ISO such as 100 or 200 will be longer shutter speed but less grain.

Also, i'd suggest manual focusing but that's just my preference.

Take the camera off "stupid" (sorry I meant auto everything) mount the camera on a tripod and shoot, be prepared for long long long exposures.

If you set your mode to P, A, S, or M mode, the camera will no longer tell you it's too dark to shoot.

However, to operate the camera in these manual modes, you'll have to learn what aperture, shutter speed, and ISO does, and how it affects your image.

In short, you'd want to have a tripod at a low ISO and high f/stop if your shooting cityscapes at night. If you're handholding the camera, you'd want to go for a high ISO and a low f/stop to prevent blur.

Take it off automatic mode and learn how to use it properly.

The advice so far is excellent. As a fine art photographer, I'll just add a few tips.

Tripod use:
You do need a sturdy tripod to take long exposures for night time photography. But I'd also recommend a cable release (or use the auto-timer feature of your camera) to prevent shaking the tripod as you press the shutter release.

"Grain":
Setting your digital camera to a very high light sensitivity (ISO number) will cause more visible digital noise to be generated by the digital light sensor and circuits in your camera. This is not really "grain". Grain only happens in chemical photography with film. But some people still call this digital sampling noise "grain".

There's not much you can do with your camera to avoid digital sampling noise at high light sensitivities - but there's software which you can use later to remove all or most of this visual noise.

I recommend "Neat Image".It's not free - prices start at $30. Works like magic though! I even use it on some of my 3D modeled, computed 3D scene renders, when my render engine produces sampling noise.

Hope this helped…
_jim coe

NOPE! Your CAMERA has no problem at all shooting in the night. YOU have problems shooting in the night. The camera is just a dumb tool, no better and no worse than the person using it. The other answers have already given you good advice on how to begin to learn to use the camera properly.