here is my code:

MyPicker.h
Qt Code: 
  1. class MyPicker : public QwtPlotPicker
  2. {
  3. public:
  4.     MyPicker( QwtPlot *plot );
  5.  
  6.     MyPicker( int xAxis = QwtPlot::xBottom,
  7.               int yAxis = QwtPlot::yLeft,
  8.               RubberBand rubberBand = CrossRubberBand,
  9.               DisplayMode trackerMode = QwtPicker::AlwaysOn,
  10.               QwtPlot *plot = NULL );
  11.  
  12.     void selectPoint( const QPointF & point );
  13.     void highlightPoint( bool isHightlight );
  14.  
  15. public slots:
  16.     // slot for SIGNAL --> void selected( const QPointF &pos )
  17.     void slotSelected( const QPointF &pos);
  18.  
  19. private:
  20.     QwtPlot *m_pQwtPlot;
  21.     QwtPlotCurve *m_pSelectedCurve;
  22.     int m_selectedPointIndex;
  23. };
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MyPicker.cpp
Qt Code: 
  1. #include "mypicker.h"
  2.  
  3. MyPicker::MyPicker(QwtPlot *plot) :
  4.     QwtPlotPicker(QwtPlot::xBottom, QwtPlot::yLeft, CrossRubberBand, QwtPicker::AlwaysOn, plot->canvas()),
  5.     m_pSelectedCurve( NULL ),
  6.     m_pQwtPlot( plot ),
  7.     m_selectedPointIndex( -1 )
  8. {
  9.     connect( this, SIGNAL( selected( const QPointF ) ), this, SLOT( slotSelected( const QPointF ) ) );
  10. }
  11.  
  12. ...
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the QtCreator shows error:
-----------------------------------------------------------------------------------------------------

QObject::connect: No such slot QwtPlotPicker::slotSelected( const QPointF ) in ..\ttt\mypicker.cpp:9

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I think the problem caused by that: SIGANL selected() defined in parent class, and SLOT slotSelected() defined in subclass.

So, how should fix the problem? Thank you in advance.