How to manually configure Qt in Eclipse for existing C++ project.

Question

I know this sounds like a stupid question but for some reason the way I'm doing it keeps giving me crashes with "symbol lookup error"/"undefined symbol".

This is what crashes:

#include <QVariantAnimation>
#include <QDebug>

class MyAnimacion : public QVariantAnimation {
public:
    MyAnimacion() : QVariantAnimation() {}
    ~MyAnimacion(){}
    void updateCurrentValue( const QVariant & value ) {}
};

int main()
{    
    MyAnimacion myAnimacion;
    return 0;    
}

If I create a clean "Qt project" with Eclipse's Qt Plugin, everything works fine. But If I do my own C++ project with the following configuration:

Qt Include Directory: /home/user/DEV/SDK/QtSDK/qt/include

Qt Link Directory: /home/user/DEV/SDK/QtSDK/qt/lib

Link Library: QtCore

It compiles and links, but crashes. Why is this?