QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = untitled7
TEMPLATE = app
SOURCES += main.cpp\
        mainwindow.cpp\

HEADERS  += mainwindow.h\



FORMS    += mainwindow.ui
INCLUDEPATH += $$PWD\include
LIBS += -Llib -lvlc-qt

My main.cpp file :

#include "mainwindow.h"
#include <QApplication>
#include <QStringList>
#include <vlc-qt/Instance.h>
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
  QStringList list{"media.mp3"};
  VlcInstance h(list);
  return a.exec();
}

When I try to run this code it shows following errors:

main.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl VlcInstance::VlcInstance(class QStringList const &,class QObject *)" (__imp_??0VlcInstance@@QEAA@AEBVQStringList@@PEAVQObject@@@Z) referenced in function main
main.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __cdecl VlcInstance::~VlcInstance(void)" (__imp_??1VlcInstance@@UEAA@XZ) referenced in function main
debug\untitled7.exe:-1: error: LNK1120: 2 unresolved externals

I have tried rebuilding the project and ran Qmake but this this error keeps showing up. What am I doing wrong ? How can I fix this ?