I am trying to call another window from a button click in python 2.7 using PyQt4. The code below opens the AddBooking dialog but immediately closes it. Im new to Gui programming, can somebody please tell me what is wrong with my code?

```
from PyQt4 import QtGui
from HomeScreen import Ui_HomeScreen
from AddBooking import Ui_AddBooking
import sys

class HomeScreen(QtGui.QWidget, Ui_HomeScreen):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.setupUi(self)
        self.show()
        self.Add_Booking_Button.clicked.connect(self.handleButton)

    def handleButton(self):
        AddBooking2()

class AddBooking2(QtGui.QWidget, Ui_AddBooking):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.setupUi(self)
        self.show()

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    window = HomeScreen()
    window.show()
    sys.exit(app.exec_())

```