diff --git a/src/message_router.py b/src/message_router.py
index 4d56153..6928be2 100644
--- a/src/message_router.py
+++ b/src/message_router.py
@@ -25,18 +25,18 @@
 
 def route_im_message(ctx: Context, conf: Config, event: MessageReceiveEvent) -> Any:
     # ignore request if sender_type is not user
-    if event.event.sender.sender_type != "user":
+    if event.event.sender.sender_type != 'user':
         return
     # ignore request if event_type is not im.message.receive_v1
-    if event.header.event_type != "im.message.receive_v1":
+    if event.header.event_type != 'im.message.receive_v1':
         return
 
     if event_is_processed(event):
-        app_logger.debug("Skip already processed: %s", attr.asdict(event.event))
+        app_logger.debug('Skip already processed: %s', attr.asdict(event.event))
         return
     if event.event.message.create_time < (time.time() * 1000 - 10 * 60 * 1000):
         # ignore event if event is 10 minutes old
-        app_logger.debug("Skip old event: %s", attr.asdict(event.event))
+        app_logger.debug('Skip old event: %s', attr.asdict(event.event))
         return
 
     myevent = MyReceiveEvent(event.event)
@@ -44,12 +44,12 @@ def route_im_message(ctx: Context, conf: Config, event: MessageReceiveEvent) ->
     if myevent.is_group_chat() and not myevent.is_mentioned_bot():
         return
 
-    feishu_logger.info("Feishu message: %s", attr.asdict(event))
+    feishu_logger.info('Feishu message: %s', attr.asdict(event))
 
     # ignore request if event has no content
     if not myevent.has_content():
         message_sender.send_text_message(myevent, '请发送包含文字或图片的消息')
-        feishu_logger.info("Skip event with no content:")
+        feishu_logger.info('Skip event with no content:')
         return
 
     done = False
@@ -64,7 +64,10 @@ def route_im_message(ctx: Context, conf: Config, event: MessageReceiveEvent) ->
         else:
             done = image_handler.handle_image(myevent)
 
-        if done:
-            mark_event_processed(event)
+        if not done:
+            message_sender.send_text_message(myevent, '生成失败！', True)
+
+        mark_event_processed(event)
+
     except Exception as e:
         message_sender.send_text_message(myevent, f'发生错误: {e}', True)