KFileDialog undefined reference

[kandalf]

Hi guys!
I'm starting to program with KDE. I have some experience on C++ and Qt and now, after a long time away from these tools, I'd like to start programming to this lovely desktop.
I started with a tutorial from Antonio Larrosa's site and I got stucked when I got this error:

MainWindow.o(.text+0x711): In function `MainWindow::fileOpen()':
/home/leonardo/development/console/kde/tutorial/src/MainWindow.cpp:67: undefined reference to `KFileDialog::getOpenURL(QString const&, QString const&, QWidget*, QString

I have included <kfiledialog.h>
Does anybody know why this can be hapenning?

Thanx a lot in advance.