diff --git a/src/main/java/org/netmelody/cieye/server/response/responder/TargetNotationHandler.java b/src/main/java/org/netmelody/cieye/server/response/responder/TargetNotationHandler.java
index cb06ef6..0c7babe 100644
--- a/src/main/java/org/netmelody/cieye/server/response/responder/TargetNotationHandler.java
+++ b/src/main/java/org/netmelody/cieye/server/response/responder/TargetNotationHandler.java
@@ -38,6 +38,7 @@ private void makeNote(final String landscapeName, final TargetId targetId, final
             if (spyIntermediary.passNoteOn(feature, targetId, note)) {
                 return;
             }
+            LOG.error("Failed to handle request to note target " + targetId.id());
         }
     }