Qt Gui Application cannot locate QGeometryData namepsace

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For some reason, my Qt5.0 is not locating the QGeometryData namespace

it displays the following error:

c:\users\jcastillo\documents\convexhull\mainwindow.h:4: error: C1083: Cannot open include file: 'QGeometryData': No such file or directory

I have attached my main, mainwindow.h and .cpp

@//mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QGeometryData>
#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
void ComputeUpperHull();

private:
Ui::MainWindow *ui;
QGeometryData top;
};

#endif // MAINWINDOW_H
@
@//mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGeometryData>

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}

MainWindow::~MainWindow()
{
delete ui;
}

void MainWindow::ComputeUpperHull()
{
top.appendVertex(QVector3D(0.0, 0.0, 0.0));
top.appendVertex(QVector3D(6.0, 3.6, 0.0)); // (v1 - v0).length() = 7.0
top.appendVertex(QVector3D(10.0, 0.6, 0.0)); // (v2 - v1).length() = 5.0
top.appendVertex(QVector3D(13.0, 3.24, 0.0)); // (v3 - v2).length() = 4.0

 // generate x (Qt::Horizontal) texture coordinates over the primitive
 top.generateTextureCoordinates();              // spread over 7 + 5 + 4 = 16

 // make a copy translated down, the copy has y texture coordinates all 0
 QGeometryData bottom = top.translated(QVector3D(0, 0, -1));

 // now modify the top so its y texture coordinates are all 1
 for (int i = 0; i < top.count(); ++i)
     top.texCoordRef(QGL::TextureCoord0).setY(1.0);

 displayList->addQuadsZipped(top, bottom);

}

@

@//main.cpp
#include <QtGui/QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);

MainWindow w;
w.ComputeUpperHull();
w.show();

return a.exec&#40;&#41;;

}

@