Qt for Python (PySide/Shiboken)

hey guys , maybe somebody can you tell me what its the wrong of my code , please :c this is the qml CustomButton { id: button x: 75 width: 150 height: 35 text: "CALCULAR" anchors.top: parent.top font.pointSize: 15 anchors.topMargin: 15 anchors.horizontalCenter: parent.horizontalCenter onClicked: { backend.multi(number1.text , number2.text) } } Connections{ target: backend function onSetMulti(result){ multiResult.text = result } and this is the python code setMulti = Signal(str) @Slot(str) #funciones def multi(self,n1,n2): result = float(n1)*float(n2) self.setMulti.emit(result)