diff --git a/src/dynamic_graph/attrpath.py b/src/dynamic_graph/attrpath.py
index ba1713ec677a619bee5926d8b4a267cb2c0bfa8e..d10778d44d6d1f94ee61125e763c571ff1162399 100644
--- a/src/dynamic_graph/attrpath.py
+++ b/src/dynamic_graph/attrpath.py
@@ -47,7 +47,7 @@ class CommandLauncher(object):
     fun=None
     def __init__(self,fun): self.fun=fun
     def __call__(self,*arg):
-        self.fun(self.mother,*arg)
+        return self.fun(self.mother,*arg)
 
 def createCommandLauncher( target,name,fun ):
     if isinstance(target,CommandPath) :