404 referrer pages when using log analytics?

Hi, our Piwik installation is importing data from Apache logs. When we run the import_logs.py script, we are adding the “–enable-http-errors” flag. However, we are find that some, but very few of the 404 error pages are listing the referrer URL. Is this because we are using log analytics? Or should this work the same as for those using javascript code?


Anybody have any ideas?