setText translation

[weixj2003ld]

1.I create a QTreeWidgetItem

QTreeWidgetItem *cities = new QTreeWidgetItem(this);
     cities->setText(0, tr("Cities"));

QTreeWidgetItem *cities = new QTreeWidgetItem(this);
     cities->setText(0, tr("Cities"));

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and use lupdate and linguist to translate "Cities" into other languages.but it can not ,and "Cities" still exist.Why?
By the way,I create a Menu,

fileMenu = menuBar()->addMenu(tr("&File"));

fileMenu = menuBar()->addMenu(tr("&File"));

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and the program can do translation.