Overloading of qwt setPen does not work - c++

Question

I wanted to compile the following code:
#include <QApplication>
#include <qwt_plot.h>
#include <qwt_plot_curve.h>
#include <qwt_plot_grid.h>
#include <qwt_symbol.h>
#include <qwt_legend.h>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QwtPlot plot;
plot.setTitle( "Plot Demo" );
plot.setCanvasBackground( Qt::white );
plot.setAxisScale( QwtPlot::yLeft, 0.0, 10.0);
plot.insertLegend( new QwtLegend() );
QwtPlotGrid *grid = new QwtPlotGrid();
grid->attach( &plot );
QwtPlotCurve *curve = new QwtPlotCurve();
curve->setTitle( "Pixel Count" );
curve->setPen( Qt::blue, 4 ),
curve->setRenderHint( QwtPlotItem::RenderAntialiased, true );
QwtSymbol *symbol = new QwtSymbol( QwtSymbol::Ellipse,
QBrush( Qt::yellow ), QPen( Qt::red, 2 ), QSize( 8, 8 ) );
curve->setSymbol( symbol );
QPolygonF points;
points << QPointF( 0.0, 4.4 ) << QPointF( 1.0, 3.0 )
<< QPointF( 2.0, 4.5 ) << QPointF( 3.0, 6.8 )
<< QPointF( 4.0, 7.9 ) << QPointF( 5.0, 7.1 );
curve->setSamples( points );
curve->attach( &plot );
plot.resize( 600, 400 );
plot.show();
return a.exec();
}
But I get the error "No matching function to call for QwtPlotCurve::setPen(...). Candidate is "QwtPlotCurve::setPen(const QPen&)". But according to the documentation (http://qwt.sourceforge.net/class_qwt_plot_curve.html#ae00bd073a2bcf7c3c810d70af1f86750) this function should be overloaded, on the one hand as setPen(const QPen&), but on the other hand as setPen(const QColor & color, qreal width = 0.0, Qt::PenStyle style Qt::SolidLine), but my QT compiler does not recognize this second overloading variable. Why? I already entered the necessary variables into the *.pro-file.
Edit: I could solve this problem by creating a QPen and added the necessary features manually, but this should only be a temporary fix...