Is the incident light dome moved away from the sensor?
Have you checked to make sure that the EV exposure modification scale set to zero?
The manual for the meter indicates the measuring angle of the sensor (30 degrees) in reflective mode.
The manual itself is available on the Gossen site under the international (outside the USA) name for the meter: Profisix
Here is a link: http://www.gossen-photo.de/pdf/ba_profisix_e.pdf