Backlight goes off in clamshell mode

[Shofar]

When my N70 is open at about 90degrees to the keyboard, my backlight goes off. Happens in most in not all programs.

When I open it up all the way and put the backlight on again all is ok unless I close it again too much to 90 degrees.

Anybody else experience this?
What if anything have you done?

Thanks,
Shofar