G4 "cannot sleep case open"...but closed!

Hi!
I recently pulled 2 scsi cards out of my mac that had been in there
for probably two years. I was really looking forward to being able to
use yhe sleep feature once again, the way I had before installing
these pci scsi cards. Only now, it(G4) says it cannot sleep because
the case is open...but its not! I have checked a dozen times looking
over the hinged/connection area to make sure nothing looks awry. Do
any of you have any ideas?
Thanx, Tom