WPF move a path programmatically

What I have is a WINFORM with an element host that hosts a WPF user control. On the wpf user control I have a Path. What i want to do is move the path on the user control, according to strings that I read from a file. Meaning, I have a loop that reads a line from the file and according to that line, "moves" the path.

My problem is that the path isn't moving on the screen. All I have is the initial path and the last position.

The code on the winform:

private void WinForm_Method()
{
     // This method invokes the method on the wpf user control

     Type t = ElemHost.Child.GetType();  
     t.InvokeMember("MovePath", System.Reflection.BindingFlags.Default | System.Reflection.BindingFlags.InvokeMethod, null, ElemHost.Child, null);
}

The code on the wpf user control:

public void MovePath()
{  
 string line = null;

 //Read data from file.
 // Every line is of the format "M x1,y1 x2,y2 x3,y3 x4,y4 x1,y1"
 using (StreamReader SR = new StreamReader("DataFile"))  
 {
   while ((line = SR.ReadLine()) != null)     
   {
     MyPath.Data = Geometry.Parse(line);
   }
 }
}