Undefined reference in Qt4 - c++

Question

I'm trying to change the user agent in Qt4.
My code:
main.cpp:
#include <QApplication>
#include <QDeclarativeContext>
#include <QDeclarativeEngine>
#include "qmlapplicationviewer.h"
#include "NetworkAccessManagerFactory.h"
#ifdef DEBUG
#include "logger.h"
#endif
Q_DECL_EXPORT int main(int argc, char *argv[])
{
QScopedPointer<QApplication> app(createApplication(argc, argv));
app->setOrganizationName("...");
app->setApplicationName("...");
QmlApplicationViewer viewer; /*and stuff related to it*/
QString userAgent("useragentstring");
NetworkAccessManagerFactory factory(userAgent);
viewer.engine()->setNetworkAccessManagerFactory(&factory);
/*showing*/
return app->exec();
}
NetworkAccessManagerFactory.h:
#ifndef NETWORKACCESSMANAGERFACTORY_H
#define NETWORKACCESSMANAGERFACTORY_H
#include <QDeclarativeNetworkAccessManagerFactory>
#include "CustomNetworkAccessManager.h"
class NetworkAccessManagerFactory : public QDeclarativeNetworkAccessManagerFactory
{
public:
explicit NetworkAccessManagerFactory(QString p_userAgent = "");
QNetworkAccessManager* create(QObject* parent)
{
CustomNetworkAccessManager* manager = new CustomNetworkAccessManager(__userAgent, parent);
return manager;
}
private:
QString __userAgent;
};
#endif // NETWORKACCESSMANAGERFACTORY_H
CustomNetworkAccessManager.h:
#ifndef CUSTOMNETWORKACCESSMANAGER_H
#define CUSTOMNETWORKACCESSMANAGER_H
#include <QNetworkAccessManager>
#include <QNetworkRequest>
class CustomNetworkAccessManager : public QNetworkAccessManager {
Q_OBJECT
public:
explicit CustomNetworkAccessManager(QString p_userAgent = "", QObject *parent = 0);
protected:
QNetworkReply *createRequest( Operation op, const QNetworkRequest &req, QIODevice * outgoingData=0 )
{
QNetworkRequest new_req(req);
new_req.setRawHeader("User-Agent", __userAgent.toAscii());
QNetworkReply *reply = QNetworkAccessManager::createRequest( op, new_req, outgoingData );
return reply;
}
private:
QString __userAgent;
};
#endif // CUSTOMNETWORKACCESSMANAGER_H
The errors are:
/home/marcin/proj/mobilitare/main.cpp:31: error: undefined reference to `NetworkAccessManagerFactory::NetworkAccessManagerFactory(QString)'
/home/marcin/proj/mobilitare/NetworkAccessManagerFactory.h:13: error: undefined reference to `CustomNetworkAccessManager::CustomNetworkAccessManager(QString, QObject*)'
What am I doing wrong? Thanks!