something about the Camera.ScreenToWorldPoint(Vector3 pos)

hi ,everyone ,here is my code piece:

Code (CSharp):

1. void FixedUpdate () {
2.        Vector3 rawPosition =Camera.main.ScreenToWorldPoint(Input.mousePosition);
3.        print (rawPosition);
4.    }

this script is attached to a simple cube.
here is the question:
the output is a fixed value instread of changing by movement of my mouse,could anyone tell me what happens?
by the way,that fixed value is the location of my MainCamera

this is my second time to post it....waitting for you guys

 

Google is your friend.

http://answers.unity3d.com/questions/134036/cameramainscreentoworldpoint-not-outputting-expect.html

 

oh,i see~ thanks