I'm having a strange problem with one site I installed WP-Piwik on today. At the beginning, it worked perfectly, but now, WP-Piwik shows 0 visitors, unique visitors, page views etc. in the overview on the WP-Piwik page and on the dashboard. The rest of the statistics work fine, which means I see the correct numbers for browsers, search engine keywords, pages visited, resolutions, OSs etc. pp. And of course, if I look into the Piwik statistics themselves, there are visitors, unique visitors, page views etc. What could be wrong?