QGLViewer subclass: linker says undefined reference to `vtable of QGLViewer'

[soroush]

Hello forum

I have a subclass of QGLViewer:
@
class GLViewer : public QGLViewer
{
Q_OBJECT
public:
explicit GLViewer(QWidget parent = 0,const QGLWidget shareWidget=0, Qt::WFlags flags=0);
protected:
void initializeGL();
void resizeGL(int width, int height);
void paintGL();
signals:
public slots:
};
@

Implementing the c'tor like this:
@
GLViewer::GLViewer(QWidget parent, const QGLWidget shareWidget, Qt::WFlags flags):
QGLViewer(parent,shareWidget,flags)
{
}
@

I'm getting linker error:

@
glviewer.o: In function GLViewer::GLViewer(QWidget*, QGLWidget const*, QFlags<Qt::WindowType>)': glviewer.cpp:(.text+0x18): undefined reference to vtable for GLViewer'
glviewer.cpp:(.text+0x20): undefined reference to `vtable for GLViewer'
@

Thanks in advance.

[GentooXativa]

You enabled the opengl at your pro file?

[soroush]

[quote author="GentooXativa" date="1334911842"]You enabled the opengl at your pro file?[/quote]

@LIBS += -lqglviewer-qt4 -lGLU@
and
@QT += core gui opengl xml glviewer@
Is that correct?