error loading controller (pr2) [closed]

edit

I am attempting this tutorial once more but strangely I have this error.

[ERROR] [1361599472.828145391, 528.673000000]: Could not load class my_controller_pkg/MyControllerPlugin: Failed to load library /home/c/fuerte_workspace/sandbox/my_controller_pkg/lib/libmy_controller_lib.so. Make sure that you are calling the PLUGINLIB_REGISTER_CLASS macro in the library code, and that names are consistent between this macro and your XML. Error string: Cannot load library: No manifest in /home/c/fuerte_workspace/sandbox/my_controller_pkg/lib/libmy_controller_lib.so: my_controller_pkg__MyControllerPlugin

It is very strange because sometimes it can load and sometimes it cannot. I don't know what is causing this error. I followed the tutorial exactly, and even tried deleting the whole package and redoing the tutorial again. Any help would be very much appreciated.

Here are some information that you might need(although I did copy it from the tutorial): controller_plugin.xml

<library path="lib/libmy_controller_lib">
  <class name="my_controller_pkg/MyControllerPlugin" 
         type="my_controller_ns::MyControllerClass"           
         base_class_type="pr2_controller_interface::Controller" />
</library>

end of my_controller_file.cpp

/// Register controller to pluginlib
PLUGINLIB_DECLARE_CLASS(my_controller_pkg,MyControllerPlugin, 
                         my_controller_ns::MyControllerClass, 
                         pr2_controller_interface::Controller)

manifest.xml

<package>
  <description brief="my_controller_pkg">

     my_controller_pkg

  </description>
  <author>c</author>
  <license>BSD</license>
  <review status="unreviewed" notes=""/>
  <url>http://ros.org/wiki/my_controller_pkg</url>
  <depend package="pr2_controller_interface"/>
  <depend package="pr2_mechanism_model"/>
  <depend package="pluginlib"/>

  <export>
    <pr2_controller_interface plugin="${prefix}/controller_plugins.xml" />
  </export>

</package>