Update to 0.5.4 - No Counting anymore

couple of days ago i updatet my Piwik core to 0.5.4 - then I noticed that
the user aren’t counted anymore.
I uploaded the Package per FTP - I tried to reinstall it (reupp).
But it neither helped to get the Piwik to work.
I dont get any Errors or something like that in the Front- and Backend.

What else can I do?
Thanks for advices,