Expected ";" when assigning variable.

var power : float = 500.0; function Start () {

 rigidbody.AddForce(Vector3(0,0,power));

}

This is all the code I am using at the moment. In the "var power : float = 500.0;" statement it says that I should put a semicolon instead of a colon. What should I do because I did it and it didn't work.