I build a rather simple pinhole using a large oatmeal box and a piece of punctured aluminum for the lens. The interior was painted flat black and the lid was covered and painted as well.

I've attempted to expose some Ilford MG rc paper five or six times always with the same result. A twenty second exposure immediately turns completely black in the developer....aaargh!

What might be going wrong?

I'm pretty sure that the camera is light tight. The plastic lid was painted black, covered with cardboard and painted black again. Its also sealed with black electrical tape.

My lens opening is tiny. I used the point of a small finishing nail to barely pierce the aluminum and lightly sanded the burs from the inside. It was sealed to the inside using super glue.

My group of nine year old Cub Scouts are finishing up their cameras too, but I don't want them to start shooting, until I know that they will work for them.

Any advise would be welcome.