Hand held and camera metering very rarely coincide. If you can get a sheet of light grey card and put it in a bright area, but away from direct light. Check the camera meter in the three settings spot centre and matrix, they should all be the same. Then the hand held meter in the same way without casing a shadow on the card and the reading should be very close tho the camera reading.

One thing to mention is the lens used on the camera should be a prime lens not a zoom. Or a zoom lens with a constant apperture. Bear in mind the hand held meter will not have to read the light levels though multiple thicknesses of glass, which, although almost certainly multicoated will reduce the light levels by perhaps up to half a stop.