Visits from search engines or campaigns are not recorded, Piwik PRO shows “There is no data for this report” for all Referrers reports.
It may happen because of:
Your pages not being tagged properly – make sure that Piwik PRO tracking code is installed on all the pages you want to track and it is not within an iframe;
You are using a redirect on your website landing page – it may happen that because of that the visitor browser is losing the referrer information. Be sure that your visitors are getting directly to the page with Piwik PRO tracking code installed;
Piwik PRO only recording one referrer by visit so only the first one used to access the website will be recorded;