unbound method () must be called with ... instance as first argument (got nothing instead)

[Mohsen Pahlevanzadeh]

Dear all,

I have the following two lines code in my setup frame:
 ////////////////////// 
 self.showHideConstructor = ui.interface.interface.ShowHide()
 QtCore.QObject.connect(self.pushButtonAdd,
QtCore.SIGNAL(_fromUtf8("clicked()")),self.showHideConstructor,ui.interface.interface.ShowHide.showFindMaterials())
//////////////////////

and i have module ui.interface.interface , it contains ShowHide class,
and it consists showFindMaterials() method.

When i run program , i get the following traceback :
///////////////////////////////////////////
Traceback (most recent call last):
  File "./main.py", line 113, in <module>
    main()
  File "./main.py", line 94, in main
    interfaceObj.showMaterials()
  File "/home/mohsen/codes/amlak/amlak/src/ui/interface/interface.py",
line 82, in showMaterials
    self.ui.setupUi(self.Frame)
  File "/home/mohsen/codes/amlak/amlak/src/ui/materialsFrame.py", line
92, in setupUi
    QtCore.QObject.connect(self.pushButtonAdd,
QtCore.SIGNAL(_fromUtf8("clicked()")),self.showHideConstructor,ui.interface.interface.ShowHide.showFindMaterials())
TypeError: unbound method showFindMaterials() must be called with
ShowHide instance as first argument (got nothing instead)
///////////////////////////////////////////////

Where's problem?