Light painting with a Nikon d300?

I'm supposed to do a light painting for photography but it's just not working for me. I have the shutter speed set and a completely dark place, after I move the flashlight around, the picture turns out as just a very dimly lit version of the area. Does anyone know what I could possibly be doing wrong?

Try this… Set to manual, including focus. Focus in the general area you plan on light paint in with the lights on manually. Set Aperture to f/13, set shutter speed to 30 seconds unless you have a remote, then use Bulb so yo can go longer with it. Set ISO to 100 or 200. Turn off the lights and start painting with the flashlight. This should get you some results. Send me an email if you have further questions on it. MRossPhoto.com has my contact info.

Try doing it with a laser pointer.