It sounds like the sensor on the camera body is faulty. You would need to have it checked out at your local service centre

By Giorgio on Monday, March 01, 2004 - 10:30 am:

Hello, i have bought 2 days ago my new Mamiya Rz 67 Pro 2 Camera and i really love this camera!
Everything work ok but i have one problem whit the dark slide shutter release prevention. I mean that if the revolving back is on horizontal position and i don't remove the dark slide from the back, the camera allow me to realase the shutter while if i rotate the back in the vertical position is all ok, i can't release the shutter and the red light glow. I have tried with 3 different mamiya back but it's always the same. Have you reported the same problem?

Thanks Giorgio