diff --git a/Media Blocks SDK/WPF/CSharp/Key Frame Detector/MainWindow.xaml.cs b/Media Blocks SDK/WPF/CSharp/Key Frame Detector/MainWindow.xaml.cs
index 9762dbacde..0f2ac7436c 100644
--- a/Media Blocks SDK/WPF/CSharp/Key Frame Detector/MainWindow.xaml.cs	
+++ b/Media Blocks SDK/WPF/CSharp/Key Frame Detector/MainWindow.xaml.cs	
@@ -119,7 +119,7 @@ await Dispatcher.InvokeAsync(() =>
             keyFrameDetector.JSONFilename = jsonFile;
             keyFrameDetector.OnKeyFrameDetected += (senderx, ex) =>
             {
-                Debug.WriteLine($"Key frame detected at {e}");
+                Debug.WriteLine($"Key frame detected at {ex}");
             };
 
             // link blocks