tv link question

[doomey!]

My in laws have run a cable up stairs to carry the HD Sky up stairs (coax), when attatching a tv link to it, the link does not work, and the picture drops to about 20 percent quality, any ideas?

[Eve]

Is Sky still being used downstairs? Think you have to have the multiroom feature to use it in different locations.

Not sure if not, maybe something to do with the cable itself? The people in Technology may know.