ok problem sorted - i think it was something to do with the fog colour - anyway i tried uding battery’s own fog colour 0.4 0.4 0.4 and the black corner has gone.
While i was sorting this i forgot to add the first line of my shader:
textures/omaha_ov/fog
and ET was not happy - not 1 texture loaded properley - let that be a warning to you - look after your shaders 