Louis,
I am not sure what exactly you are doing to couple the meter, but here goes:
- Set the camera to 'B'
- Turn the meter's shutter speed dial to 'B', lift it and turn it further past 'B'. The dial should stay up.
- Slide the meter into the camera's accesstory shoe. Turn the meter's shutter speed dial back to 'B'.
Once back to 'B', the meter's dial should pop down and engage with the camera's shutter speed dial. You can make sure at this point that the pin on the lower side of the meter dial is coupled correctly with the slot in the camera's dial. From this point on, it should stay engaged and change the camera's shuter speed.
To remove the meter, follow same procedure as in '2' above.
All the best,
Jan