Can't see any text append in UI?

[SamT]

I got a problem to use the QTextEdit with append function.

MainWindow::ui->textDumpMessage->append("Before the QStringList fileList line");
    QStringList fileList = QFileDialog::getOpenFileNames(this, tr("Open CSV"), QDir::currentPath(), tr("CSV File *.csv"));
    if (fileList.isEmpty())
    {
        return false;
    }
    MainWindow::ui->textDumpMessage->append("After the QStringList fileList line");
    qDebug() << "Load csv";

MainWindow::ui->textDumpMessage->append("Before the QStringList fileList line");
    QStringList fileList = QFileDialog::getOpenFileNames(this, tr("Open CSV"), QDir::currentPath(), tr("CSV File *.csv"));
    if (fileList.isEmpty())
    {
        return false;
    }
    MainWindow::ui->textDumpMessage->append("After the QStringList fileList line");
    qDebug() << "Load csv";

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the QTextEdit can show first append text but fail to get the second append text. I doubt the problem is on QStringList or QFileDialog. Does any body encounter the same issue?

I use QT 4.7.2 with mingw32 on windows XP.