I have a big problem that i can't solve by myself. OpenCV itself works fine, but i'm not able to load videos. Here's my code:

PRO- File
@QT += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = videoredux
TEMPLATE = app

INCLUDEPATH += C:/OpenCV/opencv_bin/install/include
LIBS += -LC:\OpenCV\opencv_bin\bin
libopencv_core248d
libopencv_highgui248d
libopencv_imgproc248d
libopencv_features2d248d
libopencv_calib3d248d
libopencv_video248d \

SOURCES += main.cpp
mainwindow.cpp

HEADERS += mainwindow.h

FORMS += mainwindow.ui@

and the MainWindow Class:
@#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QFileDialog>
#include <iostream>
#include <qdebug.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv/cv.h>

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
ui->videoStatusLabel->setText("Kein Video geladen.");

// SIGNALS & SLOTS

QObject::connect(ui->chooseVideoButton,SIGNAL(clicked()),
                 this,SLOT(chooseVideo()));
QObject::connect(ui->startButton,SIGNAL(clicked()),
                 this,SLOT(startProcess()));

}

void MainWindow::chooseVideo(){

QString fileName = QFileDialog::getOpenFileName(this,
     tr("Open Video"), "/home", tr("Video Files (*.avi *.mp4 *.mpeg *.mpg)"));
qDebug() << "Path:" << fileName;
ui->videoStatusLabel->setText(fileName);

}

void MainWindow::startProcess(){
QString videoPath = ui->videoStatusLabel->text();
QFileInfo video(videoPath);
if(video.exists()){
const std::string path = videoPath.toUtf8().constData();
cv::VideoCapture capture(path);
cv::Mat frame;

    if(!capture.isOpened()){
        qDebug() << "Error, video not loaded";
    }

    cv::namedWindow("window",1);
    while(true)
    {
        bool success = capture.read(frame);
        if(success == false){
            break;
        }
        cv::imshow("window",frame);
        cv::waitKey(20);
    }
    cv::waitKey(0);
}
else{
    qDebug() << "Error, File doesn't exist";
}

}@

The paths are correct, I tried many different video formats but he never loads the videos. I'm running Qt on a Windows 8 machine and i have "K-Lite Codec Pack 10.2.0 Basic" and ffmpeg installed. The videos are playing properly with my video players. Does anyone know how to solve this problem?

Thank you very much!

Nadine