QGraphicsScene::removeItem: item 0x8143148's scene (0x80d49d0) is different from this

[learning_qt]

I use QGraphicsScene::addItem to add item to a scene. But when I try to remove it from the scene, I got the warning:
QGraphicsScene::removeItem: item 0x8143148's scene (0x80d49d0) is different from this scene (0x80c91c8)

I just created one object for the QGraphicsScenewhat is wrong?

[lyuts]

Show your code.