But the icinga-GUI instead shows just a soft state "1/3". It seems also no notification is generated
Do you have any ideas on this?
Thats absolutly ok if you have set "max_check_attempts" to 3 (which is the default). If you want to have a notification on the first state change, youhave to set this to 1 in your service. Otherwise the service needs to be 3 times in critical state before you get a notification.