Are you comparing your reading to your camera reading ? Does your camera have spot metering or multi type metering ? I would guess that since the light meter is averaging a larger area that it would give a " false " reading. False, only in the sense that your camera could be metering on a darker portion of the subject. See what i'm getting at ?
By hot I mean, when I shoot at what the meter says to shoot at, I have to lower the exposure by about 2.5-3 stops to get my highlights back when I load the image into camera raw.
First off, what type of meter? Incident or reflected? You have to be careful "how" you are metering. Also, meters need to be calibrated to your medium, in this case, your digital sensor. Every sensor, even two identical D50s might react slghtly different, and the meter has a range that can be tweaked to match your output.