Help please with db 500s

Hope someone can help me out here ? I have 2 dreamboxes 500s which I have pli jade image on both receivers ,when I try to scan 28.2 sat I get half the channels missing like discoverys sports and even bbc although the other box has all channels.have tried scanningon several occasions but will not pick up the missing channels,is there any other way I can send a channel list via ftp if yes where do I get the files and where to put them required,its been a long time since I played around with the box and need it for the grand children.

many thanks in advance

MR-T

Thanks for the tutorial helped a lot but it turned out to be a faulty lnb plug had even put on a channel list and bbc or itv would not clear the signal was around 59% should have been in the 90's tried 3 different locations in the house and still the same then I just put coax wire in by itself and got a signal around 94% and scanned all the channels and it back up and running again.

regards
MR-T:thumb: