Rob,
Thanks for the reply. I don't know if you understand me as well as I would like. My english is a little poor (google translator is my friend 
)
This is only an example:
if evt.eventClassMapping.find("StatystykiViaSyslog") != -1:
evt.summary = "BM"
but it work. So the condition is met.
I send events from linux shell using '/opt/zenoss/bin/zensendevent' command and I receive them in the Zenoss console. But I need to set a field named 'DeviceGroups' field in the 'Device State' part. I'm trying to do it by transform. The group "BM" exist, I have some devices in this group. Why I need to do it? Because I have some users which are monitoring the events of its devices. These users have permissions to see the 'BM' group only.
Regards,
Tommy