how to solve the error ? undefined reference to `laser_geometry::LaserProjection:

edit

I am working in corverting the laserscan data to sonar data. In this task I had I have the same problem as in this question "http://answers.ros.org/question/31968/compiler-cant-find-transformlaserscantopointcloud-function/"

The answer in this question is to first download the laser_generator package. - I downloaded it using "sudo apt-get install ros-hydro-laser_geometry"

Second add the package to the dependence in the manifest file.. I dont have a manifest file, instead I have a package.xml file.

I added

  <build_depend>laser_geometry</build_depend>

and

    <run_depend>laser_geometry</run_depend>

but still didnt work and I have the error:

undefined reference to `laser_geometry::LaserProjection::~LaserProjection()'