I have a D300 Nikon and a SB900 flash. Pics are dark at any setting?

I have to raise the ISO so high just to see a pic at all and it sucks.Am I doing something wrong. I have a compatible lens. I must say I'm new to the flash on the camra.

I have found using a flash to be way more difficult than I had imagined. But once you get the hang of it, it will suddenly all make sense.
I bet your camera is fine and so is the flash.

Read your manual - both the camera AND the flash's user guides.

Go to a website called the strobist - it will take effort, but help IS available. I'm sure with a bit of reading and a bunch of effort you'll work out which settings you need on both the camera and the flash.

Set camera to manual mode. Set shutter speed to 1/125. Set ISO to lowest value. Set flash to auto mode. Set flash ISO to whatever was set on the camera. Look at what aperture size the flash recommends. Set lens aperture to that. Take a shot of something around 10 feet away. To tone down flash, set lens to lower f/number. To capture more flash light, set lens to higher f/number.

If you can't survive that method, read the camera and flash manuals.