catkin_make error when using vrpn_client_ros

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Hi, I want to connect Optitrack and ROS together, using the package vrpn_client_ros. Now, I'm using ubuntu14.04 installed ros indigo. I found the package from http://wiki.ros.org/vrpn_client_ros and git clone the code form https://github.com/clearpathrobotics/... into my folder ~/catkin_ws/src. but when I run

catkin_make

,

it came to errors like ths:

> CMake Error at
> vrpn_client_ros/CMakeLists.txt:5
> (find_package):   By not providing
> "FindVRPN.cmake" in CMAKE_MODULE_PATH
> this project has   asked CMake to find
> a package configuration file provided
> by "VRPN", but   CMake did not find
> one.
>
>   Could not find a package
> configuration file provided by "VRPN"
> with any of   the following names:
>
>     VRPNConfig.cmake
>     vrpn-config.cmake
>
>   Add the installation prefix of
> "VRPN" to CMAKE_PREFIX_PATH or set  
> "VRPN_DIR" to a directory containing
> one of the above files.  If "VRPN"  
> provides a separate development
> package or SDK, be sure it has been  
> installed.
>
>
> -- Configuring incomplete, errors occurred! See also
> "/home/sen/catkin_ws/build/CMakeFiles/CMakeOutput.log". See also
> "/home/sen/catkin_ws/build/CMakeFiles/CMakeError.log".
> Invoking "cmake" failed

Why this happen? What should I do next? I will appreciate if you could help. Thanks a lot!