How to set the position of a QDialog?

Question

I am using Ubuntu 16.04 and Python 2.7. I used PyQt to create a dialog, but how to set the position of a QDialog object? I tried self.move(x,y), but it does not move and still stays in the original position.

This is my example:

class MainWindow(QMainWindow, WindowMixin):

    def __init__(self):
         super(MainWindow, self).__init__()
         self.myDialog = MyDialog(parent=self)

    def createMyDialog(self):
        self.myDialog.popUp(x=self.geometry().x(), y=self.geometry().y(), width=self.geometry().width(), height=self.geometry().height())

class MyDialog(QDialog):

    def __init__(self, parent=None):
        super(LabelDialog, self).__init__(parent)

    def popUp(self, x="", y="", width="", height=""):
        if (x!="") and (y!="") and (width!="") and (height!=""):
            # self.resize(width/6, 20)
            self.move(0, 0)

I use the createMyDialog function to create the modal dialog. Can anyone give any advice?