This is a huge difference and I certainly would expect a much smaller difference.
Do you use another tracking package on your site, to compare with Piwik?
What would be great would be to look at your server ACCESS logs and grep for "facebook.com" to check how many referrers you REALLY got from facebook. then we could try understand why they would not all be tracked by piwik..
Do you use another tracking package on your site, to compare with Piwik?
What would be great would be to look at your server ACCESS logs and grep for "facebook.com" to check how many referrers you REALLY got from facebook. then we could try understand why they would not all be tracked by piwik..