NameError: global name 'NAME' is not defined <SOLVED>

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Hi people! :) i am listening GPS's data and i want use them in another part of my code, for do Path Planing, but when I try to use them, it give me back this error

I defined variable global (global Lon, Lat) in many places like inside of def listener(), def backlatitud(): and def backlongitud() and it give back the same error.

Traceback (most recent call last):
  File "/home/pi/ros_catkin_ws/src/ceres_pkg/src/Controlador.py", line 25, in <module>
    listener()
  File "/home/pi/ros_catkin_ws/src/ceres_pkg/src/Controlador.py", line 20, in listener
    print Lat
NameError: global name 'Lat' is not defined

This is my code:

#!/usr/bin/env python
import rospy
from std_msgs.msg import String
global Lon, Lat

def backlatitud(data1):
    Lat = float(data1.data)
    #rospy.loginfo('Latitud %s', data1.data)
    return;

def backlongitud(data):
    Lon = float(data.data)
    #rospy.loginfo('longitud %s', Lon)
    return;

def listener():
    rospy.init_node('listener', anonymous=True)
    rospy.Subscriber("/latitud", String, backlatitud)
    rospy.Subscriber("/longitud", String, backlongitud)
    print Lat
    print Lon
    rospy.spin()

if __name__ == '__main__':
    listener()