QVision and undefined reference to `vtable for QVCannyEdgeDetector' - c++

Question

I have compiled and installed QVision on Archlinux. The libraries I have choosed to be compiled with QVision were qwt,opencv and cgal.
Now I want to compile this code. But can't compile.
#include <QVApplication>
#include <QVVideoReaderBlock>
#include <QVImageCanvas>
#include <QVCannyEdgeDetector>
#include <QVDefaultGUI>
int main(int argc, char *argv[])
{
QVApplication app(argc, argv,
"Example program for QVision library. Obtains Canny borders from input video frames."
);
QVVideoReaderBlock videoReader("Video reader");
QVCannyEdgeDetector cannyBlock("Canny block");
QVImageCanvas imageDisplayer("Original image");
QVImageCanvas edgesDisplayer("Canny edges");
videoReader.linkProperty(&cannyBlock,"Input image");
cannyBlock.linkProperty("Input image",imageDisplayer);
cannyBlock.linkProperty("Output image",edgesDisplayer);
QVDefaultGUI defaultGUI;
return app.exec();
}
and this is the .pro file I have used for the qt project:
LIBS = -L /opt/QVision/lib/lib*
INCLUDEPATH = /opt/QVision/src
TARGET = canvasInteract
SOURCES += main.cpp
and these are the errors I get:
main.cpp:-1: error: undefined reference to `QVCannyEdgeDetector::QVCannyEdgeDetector(QString)'
main.cpp:-1: error: undefined reference to `vtable for QVCannyEdgeDetector'
main.cpp:-1: error: undefined reference to `vtable for QVCannyEdgeDetector'
main.cpp:-1: error: undefined reference to `vtable for QVCannyEdgeDetector'
main.cpp:-1: error: undefined reference to `vtable for QVCannyEdgeDetector'
main.cpp:-1: error: more undefined reference to `vtable for QVCannyEdgeDetector'
:-1: error: collect2: error: ld returned 1 exit status
How can I solve this problem?