"can't find linker symbol for virtual table for `QPixmap' value" what does it mean?

[Qt4dummie]

Hi,

I got a debugging error "can't find linker symbol for virtual table for `QPixmap' value", what does it mean?

void GalleryTab::setupPuzzle()
{
    ....
    puzzleWidget->drawPuzzleWidget(puzzleImage); // puzzleImage is a QPixmap
}
 
void PuzzleWidget::drawPuzzleWidget(const QPixmap aPuzzleImage){
 
    clear();
    QPoint location = QPoint(0,0);
    QRect square = QRect(0,0, m_ImageSize, m_ImageSize);
 
    pieceLocations.append(location);
    piecePixmaps.append(aPuzzleImage);
    pieceRects.append(square);
 
    update(square);
}

void GalleryTab::setupPuzzle()
{
    ....
    puzzleWidget->drawPuzzleWidget(puzzleImage); // puzzleImage is a QPixmap
}

void PuzzleWidget::drawPuzzleWidget(const QPixmap aPuzzleImage){

    clear();
    QPoint location = QPoint(0,0);
    QRect square = QRect(0,0, m_ImageSize, m_ImageSize);

    pieceLocations.append(location);
    piecePixmaps.append(aPuzzleImage);
    pieceRects.append(square);

    update(square);
}

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What did I do wrong? How do I rewrite drawPuzzleWidget() to display an image "aPuzzleImage"?

Your help is much appreciated!