Ошибки Qt программ с тестом

Я пытаюсь скомпилировать программу диалога из книги qt. Я продолжаю получать эту ошибку:

: ‘QLabel’: класс не имеет конструкторов

про:

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = untitled
TEMPLATE = appSOURCES += main.cpp\
mainwindow.cpp \
finddialog.cpp

HEADERS  += mainwindow.h \
finddialog.h

FORMS    += mainwindow.ui

главный:

#include <QApplication>
#include "finddialog.h"int main(int argc, char *argv[])
{
QApplication app(argc, argv);
FindDialog *dialog = new FindDialog;
dialog->show();
return app.exec();
}

Заголовок:

#ifndef FINDDIALOG_H
#define FINDDIALOG_H

#include <QDialog>

class QCheckBox;
class QLabel;
class QLineEdit;
class QPushButton;
class QWidget;

class FindDialog : public QDialog
{
Q_OBJECT
public:
FindDialog(QWidget *parent = 0);
signals:
void findNext(const QString &str, Qt::CaseSensitivity cs);
void findPrevious(const QString &str, Qt::CaseSensitivity cs);
private slots:
void findClicked();
void enableFindButton(const QString &text);
private:
QLabel *label;
QLineEdit *lineEdit;
QCheckBox *caseCheckBox;
QCheckBox *backwardCheckBox;
QPushButton *findButton;
QPushButton *closeButton;
};

#endif // FINDDIALOG_H

Воплощать в жизнь:

#include <QtGui>

#include "finddialog.h"
FindDialog::FindDialog(QWidget *parent) : QDialog(parent)
{
label = new QLabel(tr("Find &what:"));
lineEdit = new QLineEdit;
label->setBuddy(lineEdit);

caseCheckBox = new QCheckBox(tr("Match &case"));
backwardCheckBox = new QCheckBox(tr("Search &backward"));

findButton = new QPushButton(tr("&Find"));
findButton->setDefault(true);
findButton->setEnabled(false);

closeButton = new QPushButton(tr("Close"));

connect(lineEdit, SIGNAL(textChanged(QString)), this, SLOT(enableFindButton(QString)));
connect(findButton, SIGNAL(clicked()), this, SLOT(findClicked()));
connect(closeButton, SIGNAL(clicked()), this, SLOT(close()));

QHBoxLayout *topLeftLayout = new QHBoxLayout;
topLeftLayout->addWidget(label);
topLeftLayout->addWidget(lineEdit);

QVBoxLayout *leftLayout = new QVBoxLayout;
leftLayout->addLayout(topLeftLayout);
leftLayout->addWidget(caseCheckBox);
leftLayout->addWidget(backwardCheckBox);

QVBoxLayout *rightLayout = new QVBoxLayout;
rightLayout->addWidget(findButton);
rightLayout->addWidget(closeButton);
rightLayout->addStretch();

QHBoxLayout *mainLayout = new QHBoxLayout;
mainLayout->addLayout(leftLayout);
mainLayout->addLayout(rightLayout);
setLayout(mainLayout);

setWindowTitle(tr("Find"));
setFixedHeight(sizeHint().height());
}

void FindDialog::findClicked()
{
QString text = lineEdit->text();
Qt::CaseSensitivity cs =
caseCheckBox->isChecked() ? Qt::CaseSensitive
: Qt::CaseInsensitive;
if (backwardCheckBox->isChecked()) {
emit findPrevious(text, cs);
} else {
emit findNext(text, cs);
}
}

void FindDialog::enableFindButton(const QString &text)
{
findButton->setEnabled(!text.isEmpty());
}