I notice that one of my big CTR link units only gets a 7% coverage I'm assuming that means 93% of the time there are no relevent ads to show Does that mean they are all Public Service ADs being shown? Any idea what I can do to increase the potential revenue on a link unit my website is quite a long tail niche site on nostalgia (skooldays.com) So it may just be there are no adverts associated with a "1950s Bally Pinball Machines" or a "1980s Rubics cube"
My link unit is at 0.07% ... the rest of my ads are at 100%. I think they work out coverage differently for link units.