Pyqt : QGraphicsView use addItem Error

When I would like to adda Line Item in the View
system send message
" ‘builtin_function_or_method’ object has no attribute ‘addItem’"
or ‘NoneType’ object has no attribute ‘addItem’
can you help me?

the following is the error line of my code
can I already check ‘start’ and ‘end’ is a position

                   self.view.scene.addItem(QGraphicsLineItem(QLineF(start,end)))

Did you mean QGraphicsScene.addItem(......) ?

https://www.riverbankcomputing.com/static/Docs/PyQt4/qgraphicsscene.html#addItem