diff --git a/examples/observer/__main__.py b/examples/observer/__main__.py
index cfb2e93..e8d97d6 100644
--- a/examples/observer/__main__.py
+++ b/examples/observer/__main__.py
@@ -4,20 +4,25 @@ import vban_cmd
 class Observer:
     def __init__(self, vban):
         self.vban = vban
+        # register your app as event observer
+        self.vban.subject.add(self)
+        # add level updates, since they are disabled by default.
+        self.vm.event.add("ldirty")
 
+    # define an 'on_update' callback function to receive event updates
     def on_update(self, subject):
         if subject == "pdirty":
             print("pdirty!")
-        if subject == "ldirty":
+        elif subject == "ldirty":
             info = (
-                f"[{self.vban.bus[0]} {self.vban.bus[0].levels.is_updated}]",
-                f"[{self.vban.bus[1]} {self.vban.bus[1].levels.is_updated}]",
-                f"[{self.vban.bus[2]} {self.vban.bus[2].levels.is_updated}]",
-                f"[{self.vban.bus[3]} {self.vban.bus[3].levels.is_updated}]",
-                f"[{self.vban.bus[4]} {self.vban.bus[4].levels.is_updated}]",
-                f"[{self.vban.bus[5]} {self.vban.bus[5].levels.is_updated}]",
-                f"[{self.vban.bus[6]} {self.vban.bus[6].levels.is_updated}]",
-                f"[{self.vban.bus[7]} {self.vban.bus[7].levels.is_updated}]",
+                f"[{self.vban.bus[0]} {self.vban.bus[0].levels.isdirty}]",
+                f"[{self.vban.bus[1]} {self.vban.bus[1].levels.isdirty}]",
+                f"[{self.vban.bus[2]} {self.vban.bus[2].levels.isdirty}]",
+                f"[{self.vban.bus[3]} {self.vban.bus[3].levels.isdirty}]",
+                f"[{self.vban.bus[4]} {self.vban.bus[4].levels.isdirty}]",
+                f"[{self.vban.bus[5]} {self.vban.bus[5].levels.isdirty}]",
+                f"[{self.vban.bus[6]} {self.vban.bus[6].levels.isdirty}]",
+                f"[{self.vban.bus[7]} {self.vban.bus[7].levels.isdirty}]",
             )
             print(" ".join(info))
 
@@ -25,7 +30,6 @@ class Observer:
 def main():
     with vban_cmd.api(kind_id, **opts) as vban:
         obs = Observer(vban)
-        vban.subject.add(obs)
 
         while cmd := input("Press <Enter> to exit\n"):
             if not cmd: