Can't link static freetype library in Qt

[Row_Rebel]

I'm getting LNK2019: unresolved externals for every freetype function referenced in my main.cpp

Here's the .pro file

#-------------------------------------------------
#
# Project created by QtCreator 2015-12-13T23:52:13
#
#-------------------------------------------------

QT       += core gui opengl

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = Tentativo6
TEMPLATE = app


INCLUDEPATH += C:/..../freetype2
LIBS += C:/..../lib/freetype.lib

SOURCES += \
    main.cpp

I'm calling those functions in my init() function this way:

FT_Library ft;
    if (FT_Init_FreeType(&ft))
         qDebug() << "ERROR::FREETYPE: Could not init FreeType Library";
    FT_Face face;
    if (FT_New_Face(ft, "C:/Users/Domenico/Desktop/DejaVuLGCSansMono.ttf", 0, &face))
    //other freetype functions

These is my include hierarchy so far:

#include <QGuiApplication>
#include <QOpenGLContext>
#include <QWindow>
#include <QOpenGLFunctions_3_3_Core>
#include <stdio.h>
#include <QMouseEvent>
#include <QVBoxLayout>
#include <QTimer>
#include <QDebug>
#include <QTime>

#include <ft2build.h>
#include FT_FREETYPE_H

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#include "shader.h"
#include "camera.h"

I already tried to clean up the solution and to run several times qmake before building again, yet I got no luck and I still see those reference errors

I also tried to specify includes and lib path with -L -l and by using the horrible "add library" wizard, still same errors are showing

Any help appreciated, thanks in advance