diff --git a/brkraw/lib/utils.py b/brkraw/lib/utils.py
index a75d5f2..c61f038 100644
--- a/brkraw/lib/utils.py
+++ b/brkraw/lib/utils.py
@@ -263,7 +263,7 @@ def meta_check_source(key_string, acqp, method, visu_pars):
     for i, ans in enumerate(key_exist):
         if ans:
             return get_value(pool[i], key_string)
-    return key_string
+    return None
 
 
 def yes_or_no(question):