diff --git a/python_package/src/onlinemid/utils/image_plotting.py b/python_package/src/onlinemid/utils/image_plotting.py
index ff6546df0f10929df3d6a84d565f647e5e87bff3..a0dc69b4a56143c4732ec855163dbee1d150d34a 100644
--- a/python_package/src/onlinemid/utils/image_plotting.py
+++ b/python_package/src/onlinemid/utils/image_plotting.py
@@ -103,7 +103,8 @@ class DataToPlotToHash():
     def is_hash_key_registered(self, hash_key):
         if hash_key not in self.hash_keys_and_plotter:
             print(f"key {hash_key} does not exist, call 'register' function in initialization() part of this karabo device!")
-            return hash
+            return False
+        return True
         
     def register(self, hash_key, Plotter):
         if hash_key not in self.hash_keys_and_plotter: