Windows 7 - Trying to set up satellite via media center and dvbs-2 box (no luck!)

I am trying to set up and watch satellite channels via my HD Star dvb-2 usb box and vista media center( sorry but I cant find a vista forum.)
I have the dvbs-2 box connected to a sky dish which is supplying us with sky channels on contract to our TV and we have run a cable from a spare lbn to the box to receive "free" satellite channels. Using Dvdviewer we are able to scan Astra/eurobird and receive razor sharp picture on all channels and this proved pretty straightforward to set up.
On the other hand using vista media center when I try and scan tv channels and transponders the only one that seem to show up is Amos with what seems a full signal. Although this is not the satellite I want I have tried playing any channels from its findings and they do not play with a message "no signal found".
Anyway my question is why am I able to pick up Astra/Eurobird with no problem on DVBviewer and play perfect picture TV but when I try and use media centre(using exactly the same equipment and cables) I am not able to even get Astra/Eurobird recognised and subsequently play all the programmes that Dvb viewer does. Any ideas thanks