OpenCv error: Assertion faild (!empty()) in cv::CascadeClassifier::detectMultiScale

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Hi Friends I'm trying to do face detection using OpenCv 3.0.0, I think something is wrong because when I run my project I face this error:

Unhandled exception at at 0x00007FFD630CAB78 in shapeDetection.exe: Microsoft C++ exception: cv::Exception at memory location 0x000000D92794F810.

and in console it's printed:

OpenCv error: Assertion faild (!empty()) in cv::CascadeClassifier::detectMultiScale

I read different posts about it, but none of them could help me. here is my code:

// shapeDetection.cpp : Defines the entry point for the console application. //

#include "stdafx.h"
#include <opencv2\highgui\highgui.hpp>
#include <opencv2\imgproc\imgproc.hpp>
#include <opencv2\objdetect\objdetect.hpp>
#include <iostream>

using namespace cv;
using namespace std;


    //load face cascade
    CascadeClassifier faceCascade;

void detection(Mat frame)
{
    //Detect faces
    vector<Rect> faces; 
    faceCascade.detectMultiScale(frame,faces,1.1, 3, CV_HAAR_FIND_BIGGEST_OBJECT|CV_HAAR_SCALE_IMAGE,Size(300,300) );

    // Draw circles on the detected faces
    for( int i = 0; i < faces.size(); i++ )
    {
        Point center( faces[i].x + faces[i].width*0.5, faces[i].y + faces[i].height*0.5 );
        ellipse( frame, center, Size( faces[i].width*0.5, faces[i].height*0.5), 0, 0, 360, Scalar( 255, 0, 255 ), 4, 8, 0 );
    }

        imshow("Video",frame);
}

int _tmain(int argc, _TCHAR* argv[])
{

    VideoCapture cap(0);
    if(!cap.isOpened())
        return -1;

    //creating window
    namedWindow("Video",CV_WINDOW_AUTOSIZE);
    faceCascade.load("C:\opencv\sources\data\haarcascades_cuda\haarcascade_frontalface_alt2.xml");

    Mat frame;
    while (1)
    {

        cap.read(frame);
        waitKey(30);
        if(!frame.empty())
        {
            detection(frame);
        }
        else
        {
            cout<<"there is no frame"<<endl;
        }

    }

    return 0;
}