Klient/Server - kłopot z przesyłem danych (QString)

 
// klient
void Widget::ReceiveData()
{
    // ta 'metoda' działa..
    //QByteArray in = client.readAll();
    //QString data(in);

    // ta nie bardzo..
    QDataStream in(&client);
    in.setVersion(QDataStream::Qt_4_0);

    if (dataSize == 0) { //dataSize - qint16
        if (client.bytesAvailable() < (int)sizeof(quint16))
            return;

        in >> dataSize;
   }

    if (client.bytesAvailable() < dataSize)
        return;

    QString rec;
    in >> rec;

    qDebug() << rec;
}

 
// serwer
void Widget::SendData()
{
    //to 'metoda' działa
    //client->write("play",4);

    //ta nie bardzo..
    QByteArray block;
    QDataStream out(&block, QIODevice::WriteOnly);
    out.setVersion(QDataStream::Qt_4_0);
    out << (quint16)0;
    out << "play";
    out.device()->seek(0);
    out << (quint16)(block.size() - sizeof(quint16));

    client->write(block);
    client->disconnectFromHost();
    client->waitForDisconnected();
}