Cannot centre window, even when parent is set

[David]

I am unable to centre a child dialog window of type RadWindow. I create the window as following:

NewGoalWindow view = new NewGoalWindow();
view.WindowStartupLocation = WindowStartupLocation.CenterOwner;
view.Owner = WindowHelper.MainWindow;
NewGoalViewModel model = new NewGoalViewModel();
model.RequestClose += delegate
{
  view.Close();
};
view.DataContext = model;
view.ShowDialog();

The window is always located in the top left corder. WindowHelper.MainWindow is a reference to a RadWindow, which I have checked is the main window of the application.

I need help. Am I overlooking something?

[David]

This has been resolved. I think there was a theme that I had applied that messed up the positioning of windows.