diff --git a/raspberry/roberto/Serial.py b/raspberry/roberto/Serial.py
index cfa7f5f..c5c3d08 100644
--- a/raspberry/roberto/Serial.py
+++ b/raspberry/roberto/Serial.py
@@ -4,7 +4,7 @@ import threading
 import serial
 
 class Serial(object):
-    self._callbacks = dict()
+    _callbacks = dict()
 
     def __init__(self, devicename='/dev/ttyUSB0', baudrate=115200):
         self.devicename = devicename
@@ -50,9 +50,10 @@ class Serial(object):
                     print(data)
                     command = data[0]
                     argument = data[2:]
-                    cb = self._callbacks[command]
-                    if cb:
-                        cb(argument)
+                    if command in data:
+                        cb = self._callbacks[command]
+                        if cb:
+                            cb(argument)
                         
         except serial.SerialException:
             pass