Event Filter doesnt work as expected

I tried to override the keypressevent for my lineEdit control using eventFiltering.
but when i run my application it doesnt do anything! i even set a break point inside the eventFiltering method , but i never get there!!?
This is my source codes :
MainWindow.h

Code:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
 
namespace Ui {
class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
 
protected:
    bool eventFilter( QObject* sender, QEvent* event);
 
private:
    Ui::MainWindow *ui;
};
 
#endif // MAINWINDOW_H

MainWindow.cpp:

Code:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "QMessageBox"
#include <QKeyEvent>
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}
 
bool MainWindow::eventFilter(QObject *sender, QEvent *event)
{
    if (sender == ui->lineEdit)
    {
        if(event->type()== QEvent::KeyPress)
        {
            QKeyEvent * keyEvent = (QKeyEvent*)(event);
            if( keyEvent->key() == Qt::Key_Control)
            {
                QMessageBox::information(this,"Salam","Test");
                return true;
            }else
            {
                 return false;
            }
        }
    }
    return QWidget::eventFilter(sender,event);
}
 
MainWindow::~MainWindow()
{
    delete ui;
}