Nikon D100 Error

[alok]

Hi

I am using a Nikon D100 with a Quantary 70-300mm lense,
and two zoom lenses (teleconverters 2x and 1.4x).

When I click to take the picture, it shows OFF (blinking)
at the control panel (in place of shutter speed). And doesnt
take picture.

One out of 5 times, it does take pictures. But other times it
will just show OFF.

I am working on an optical experiment. If any body could
solve this, it would be really appreciable, as I just have 2-3 more
days to work on this experiment before I leave this place.

Best
Alok