Web Acceleration, Analytics and Splunk

Hi! I wanted to get statistics about how much web traffic is served from the cache of our Big-IP (12.1.0). I used this howto to setup an analytics profile and the internal and external logging. The gathering of the statistics is working locally on the Big-IP, but not on splunk (at least it doesn´t seem to). The splunk server receives audit logs, etc. but no statistics. Does anyone of you already have successful configured this? Can you give me some examples how the analytics logging should look like in splunk? Do I need the f5 add-on for splunk? Thanks!