BH

Hello, I have encountered a problem starting the gazebo simulator. I'm using the indigo ros distribution and gazebo 2.2.I'm following the installation tutorial and when I reach the stand-alone Gazebo works section, I try to type the gazebo command and I receive the following error:

Error [RTShaderSystem.cc:409] Unable to find shader lib. Shader generating will fail.Error [Server.cc:285] Could not open file[worlds/empty.world]

What could cause this?