Qwt: Unable to draw the label from qwtplotmarker?

Sir, this is my code:-
in .h file

Code:

class Marker:public QwtPlotMarker{
 
 
  public:
    virtual void drawLabel(QPainter *painter, const QRectF &, const QPointF &pt) const{
        painter=new QPainter;
        QImage pixx(":/Images/AlarmEvent.png");
         QRectF r(1,1,10,10);
        painter->drawImage(r,pixx);
    }
};

in .cpp file

Code:

Marker *mark;
    mark=new Marker;
    mark->setValue(xData_1.at(0),yData_1.at(0));//this is where i want to place the marker.
    mark->attach(plot);

Sir, it is not showing any label on the marker. Why is this happening? Is something wrong in the code? Please Guide Me.