QT GUI Thread

I have a problem with assigning a parent to the thread in the constructor of the dialog constructor:

Code:

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
    thread_ptr=new Mythread(this);      //    <------------ here is the problem
    connect(thread_ptr,SIGNAL(valueChanged(int)),this,SLOT(On_value_changed(int)));
 
}

The error as follows:

Code:

error: no matching function for call to 'Mythread::Mythread(Dialog*)'
          thread_ptr=new Mythread(this);
                                 ^