python - signal with PyQt4.8 -

i connect simple signal @ combo :

def __init__(self, main_window, model):     """     :type main_window: odawindow     """      self.model = model      self.mapper = qdatawidgetmapper(self.ui.frame_destination_body)       self.ui.combo_box_info_body_otp.currentindexchanged.connect(self.mapper.setcurrentindex)      self.ui.combo_box_info_body_otp.currentindexchanged.connect(self.print_hello)  @pyqtslot() def print_hello(self):     print("hello") 

the mapper.setcurrentindex ok not print_hello, know if general problem of pyqt(4.8) or if don't use correctly signal. have similar problem signal of push_button

thank in advance