Python-сообщество

#!usr/bin/env python
# -*- coding: utf-8 -*-
from PyQt4 import QtCore, QtGui, uic
import sys, time
def on_clicked ():
	time.sleep(10)
app = QtGui.QApplication(sys.argv)
window = uic.loadUi(u"lab.ui")
button = QtGui.QPushButton (u"Посчитать")
QtCore.QObject.connect(button, QtCore.SIGNAL("clicked"), on_clicked() )
window.show()
sys.exit(app.exec_())

Traceback (most recent call last):
  File "D:/WORK/true/laba.py", line 12, in <module>
    QtCore.QObject.connect(button, QtCore.SIGNAL("clicked"), on_clicked() )
TypeError: arguments did not match any overloaded call:
  QObject.connect(QObject, SIGNAL(), QObject, SLOT(), Qt.ConnectionType=Qt.AutoConnection): argument 3 has unexpected type 'NoneType'
  QObject.connect(QObject, SIGNAL(), callable, Qt.ConnectionType=Qt.AutoConnection): argument 3 has unexpected type 'NoneType'
  QObject.connect(QObject, SIGNAL(), SLOT(), Qt.ConnectionType=Qt.AutoConnection): argument 2 has unexpected type 'str'

QtCore.QObject.connect(button, QtCore.SIGNAL("clicked"), on_clicked() )

QtCore.QObject.connect(button, QtCore.SIGNAL('clicked()'), someFunc)