如何使用QtGui更新类中的Label

Question

form_class = uic.loadUiType("GUI.ui")[0]  # Load the UI


class MainWindowClass(QtGui.QMainWindow, form_class):
 def __init__(self, target, Afb, np, conversion, parent=None):
    QtGui.QMainWindow.__init__(self, parent)
    self.setupUi(self)
    self.startButton.clicked.connect(self.startProgramm)  
    self.target = target
    self.Afb = Afb
    self.np = np
    self.conversion = conversion


 def update_Label(self):
    leistung = self.IcBox.value() * self.UceBox.value()
    self.Leistunglabel.setNum(leistung)

我的Python课程的一部分。我也尝试过datatime但它不起作用。