HTTP POST method

[Macok]

I have a problem with a HTTP post method.

Here's an example:
Go to http://www.ddo.com/, type "BLABLA" in search area and press ENTER.
You will get "Total: 0 Results found for "BLABLA"".

I want to reach the same effect using Qt, I tried this:

void MainWindow::on_pushButton_clicked()
{
    http=new QHttp("www.ddo.com");
    connect(http, SIGNAL(readyRead(QHttpResponseHeader)), this, SLOT(readResponse(QHttpResponseHeader)));
    http->post("/component/search/", "searchword=BLABLA");
}
 
void MainWindow::readResponse(QHttpResponseHeader header){
    qDebug()<<http->readAll();
}

void MainWindow::on_pushButton_clicked()
{
    http=new QHttp("www.ddo.com");
    connect(http, SIGNAL(readyRead(QHttpResponseHeader)), this, SLOT(readResponse(QHttpResponseHeader)));
    http->post("/component/search/", "searchword=BLABLA");
}

void MainWindow::readResponse(QHttpResponseHeader header){
    qDebug()<<http->readAll();
}

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http->readAll() returns source code of site http://www.ddo.com/component/search/, but in source this expression:
Total: 0 Results found for "BLABLA"
doesn't exist. Instead, there's:
Total: 0 Results found for ""

So it looks like server didn't receive any post data.
I tried this on more websites, and every time server ignores my post data.

What's wrong?

Thanks in advance!