Scroll bars in scroll area not comming

[aurora]

Hi all,
Using Qt designer i created a Scroll area, and in run, dynamically adding widgets inside it...
But unfortunately, widgets are added but scroll bar not coming...Because of this only few widgets are visible....

I searched in forum, many r unresolved problems...
Please help me to sort out my problem
this is the code....

void MainWindow::on_pushButton_clicked()
{
  QLabel *label =new QLabel;
  label->setText("hello");
  ui->verticalLayout->addWidget(label,10);
 
 
}

void MainWindow::on_pushButton_clicked()
{
  QLabel *label =new QLabel;
  label->setText("hello");
  ui->verticalLayout->addWidget(label,10);


}

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i set scroll bar policy as always on....