I am in the black crystal room and have entered the correct symbols and numbers in their respective spaces. I have hit the left red button to get violet shade and have slid the slider on right hand side to violet. I then go up turn around and hit the red button. There is a flash of purple light but the green square on door does not light up just the red one. What am I doing wrong.

Thanks footprints

Hi footprints,

Check this old thread. See if it might help.
It might be best to replay that room with particular care for the Rhem cardinal points as well as the pads at each corners. Keep us posted.

cool game but very hard in some places.good luck.