Thanks Huevos.
I was beginning to think that it was a miss match.
The point of the Unicable LNB is that I can use it on my VU+ (happily recording 5 concurrent recordings, I haven't tried on more than that) and connect other boxes to it in the future. The down side is that I would have liked to feed the Skybox from it which is only working on 1 feed.
All this through 1 wire which is what I have in this house.