[ZendTo] statistics don't work

[tw2006]

Hi all,
  i download few month ago zendto vmware machine based on  centos and all
works fine, but statistics don't work anymore, i have only stats about
november and december

what i can check?, the path on preferences.php about RRD is corrects

thanks
Riccardo
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ecs.soton.ac.uk/pipermail/zendto/attachments/20130218/103420a1/attachment.html