diff --git a/apps/third/dahua.py b/apps/third/dahua.py
index f8f69400..6f4a0ab1 100644
--- a/apps/third/dahua.py
+++ b/apps/third/dahua.py
@@ -135,9 +135,11 @@ class DhClient:
             json_data['deviceCode'] = d_code
             json_data['params'] = '{\"method\":\"dev.snap\",\"id\":123,\"params\":{\"DevID\":\"' + \
                 str(d_code) + '\",\"DevChannel\":' + str(num) + ',\"PicNum\":1,\"SnapType\":1,\"CmdSrc\":0}}'
-        _, res = self.request(**dhapis['dev_snap'], json=json_data)
-        res = json.loads(res)
-        return self.get_full_pic(res['params']['PicInfo'])
+        is_ok, res = self.request(**dhapis['dev_snap'], json=json_data)
+        if is_ok == 'success':
+            res = json.loads(res)
+            return self.get_full_pic(res['params']['PicInfo'])
+        return None
 
     def get_password_token(self):
         _, res = self.request(**dhapis['oauth_key'])