How to use UserCamera->ViewController()?

edit

I am running gazebo2.2.

I want to control UserCam ,and looked up in API doc(http://osrf-distributions.s3.amazonaws.com/gazebo/api/2.2.1/classgazebo11rendering11UserCamera.html#a7148635d156d63c3e163bf1c28bb547e)

I found three function as following:

EnableViewController(TRUE); SetFocalPoint(math::Vector3(0,0,0.1)); SetViewController("orbit",math::Vector3(0,1,0.5));

So , I imaged that my userCam would orbit the point(0,0,0.1)

but, It turned out nothing happened!

Did I miss some steps?

Thank you~!

if it is possible, can you check my code?

Here is my code: http://pastebin.com/emWnSf00