ImportError: No module named msg

edit

I have googled a lot of solutions, but none have worked. I follow exactly the same as http://wiki.ros.org/ROS/Tutorials/CreatingMsgAndSrv#Creating_a_msg. Is there anything I missed?

my python script

import rospy
import cv2
from sensor_msgs.msg import Image
from sensor_msgs.msg import LaserScan
from face_detection.msg import TwoPoints

The error message

Traceback (most recent call last):   File "/home/tlkoo/catkin_ws/src/face_detection/src/face_detection.py", line 10, in <module>
    from face_detection.msg import TwoPoints   File "/home/tlkoo/catkin_ws/src/face_detection/src/face_detection.py", line 10, in <module>
    from face_detection.msg import TwoPoints ImportError: No module named msg

in my package.xml

  <build_depend>message_generation</build_depend>
  <build_export_depend>message_generation</build_export_depend>
  <exec_depend>message_runtime</exec_depend>


  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>roscpp</build_depend>
  <build_depend>rospy</build_depend>
  <build_depend>sensor_msgs</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_depend>visualization_msgs</build_depend>
  <build_depend>geometry_msgs</build_depend>

  <build_export_depend>geometry_msgs</build_export_depend>
  <build_export_depend>visualization_msgs</build_export_depend>
  <build_export_depend>roscpp</build_export_depend>
  <build_export_depend>rospy</build_export_depend>
  <build_export_depend>sensor_msgs</build_export_depend>
  <build_export_depend>std_msgs</build_export_depend>
  <exec_depend>roscpp</exec_depend>
  <exec_depend>rospy</exec_depend>
  <exec_depend>sensor_msgs</exec_depend>
  <exec_depend>std_msgs</exec_depend>

my CMakeLists.txt

cmake_minimum_required(VERSION 2.8.3)
project(face_detection)

## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)

## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages
find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  sensor_msgs
  std_msgs
  cv_bridge
  geometry_msgs
  visualization_msgs
  message_generation
#  opencv2
)

add_message_files(
   FILES
   pt.msg
   TwoPoints.msg
)

generate_messages(
   DEPENDENCIES
   sensor_msgs
   visualization_msgs std_msgs geometry_msgs
)

catkin_package(
   CATKIN_DEPENDS
   message_runtime
)

I have tried lot of "solution" found, e.g. roslib.load_manifest(), catkin_make install,