Why is it not working?

Question

So I went to get a app today, and I was told from someone that its better to do it when your phone is hooked up to your comp. So I did it through Itunes I click get app then agreed to Itunes on w.e there agreeing thing was saying I then went to sync my phone to get it and it said that this app was not installed on the iPhone "My name" cause you are not authorized for it on the computer. This is the computer I used to hook up this iphone (3g) and everything. Why isn't this working?

Answer 1

O.k, this is my GravField class, now the error occurs when i try to call this in my main metod class, which i put up previously. I always compile to make sure everything works and it does in the GravField class, however when i call the method in my main method thats where the above error occurs. (Thanks for taking the time, really appreciate it!)
public class GravField
  private final double M = 5.974E24;
  private final double R = 6380e3;
  private double Mass;
  private double Radius;
  public GravField()
    Mass = 1;
    Radius = 1;
    return;
  public GravField(double r, double m)
    Radius = r;
    Mass = m;
    return;
  public void setRadius(double r)
    Radius = r;
    return;
  public void setMass(double m)
    Mass = m;
    return;
  public double getMass()
    return Mass;
  public double getRadius()
    return Radius;
  public PhysicsVector Accel(PhysicsVector w) //w is position vector
     PhysicsVector g = new PhysicsVector();  // g = (0,0)     
     double G = 6.673E-11;
     double x = g.getX();
     double y = g.getY();
     double z = w.getX();
     double zz = w.getY();
     if(w.magnitude()>Radius*R) {
     x = (z*-G*M*Mass)/(w.magnitude()*R*Radius*R*Radius);
     y = (zz*-G*M*Mass)/(w.magnitude()*R*Radius*R*Radius); }
     else
     { x = (z*-G*M*Mass*Radius*R)/(w.magnitude()*R*Radius*R*Radius*R*Radius);
       y = (zz*-G*M*Mass*Radius*R)/(w.magnitude()*R*Radius*R*Radius*R*Radius);
     return g;
}