AIW9000 Composite video input problem

When I select composite video as the input within MMC (or indeed any
software which can capture through my AIW card) I just get a black
screen. The Composite video signal is certainly getting to the 4 headed
input block - in fact if I take the same connector out of the composite
video input socket and plug it into the SV input next to it, (via an RCA
to SV adapter) the picture comes through when I select SV as the input.

Does anyone have any idea why this could be happening? It hadn't used to
up until a week or so ago. I have uninstalled and reinstalled all the
software elements, and I'm satisfied that everything else is working fine.

Yours, scratching his head....


Kettle