No referrer URL logged for this click!

Hi
I get the " No referrer URL logged for this click!" reference quite a  lot in a new campaign I'm running. What does it mean? Can it be a sign of click-fraud?
Thank you for your help!
Regards
RedSaint

It shouldn't happen often. Sometimes the browser information doesn't carry a referrer, that's just the nature of the web. Sometimes bots come to your site and there is no referrer with them. But if it's happening often there is a problem. Click fraud can be detected if you see clicks constantly from the same IP. In any case can you either PM me or send a message via the contact link with your username so we can look into the issue.

Thanks,
Larry