Why does OpenCV recognize the object only in training images? [closed]

edit

In order to make my iOS app recognize 1€, 2€ and 0.50€ coins I have been trying to use opencv_createsamples and opencv_traincascade to create my own classifier.xml. So, I cropper 60 images of 2€ coins from a short video like the following:

Then, I combined them with random backgrounds using opencv_createsamples. I obtained 12000 images similar to this:

and I ran the following commands:

opencv_createsamples -img positives/i.jpg -bg negatives.txt -info i.txt -num 210 -maxidev 100 -maxxangle 0.0 -maxyangle 0.0 -maxzangle 0.9 -bgcolor 0 -bgthresh 0 -w 48 -h 48 (for i from 0 to 60)

cat *.txt > positives.txt

opencv_createsamples -info positives.txt -bg negatives.txt -vec 2.vec -num 12600 -w 48 -h 48

opencv_traincascade -data final -vec 2.vec -bg negatives.txt -numPos 12000 -numNeg 3000 -numStages 20 -featureType LBP -precalcValBufSize 2048 -precalcIdxBufSize 2048 -minHitRate 0.999 -maxFalseAlarmRate 0.5 -w 48 -h 48

Training stopped at 13-th stage. Once I got a cascade.xml I tried it at once (with detectMultiScale()) on a simple image taken by my smartphone but nothing is detected:

while if I give as input one of the images used as traning, then it works very good:

I can't really understand why this is happening and it's driving me insane, most of all because I have been trying to make it work for weeks...would you please tell me where I am making the mistake?

The short program I wrote is here:

#include "opencv2/opencv.hpp"

using namespace cv;

int main(int, char**) {

Mat src = imread("2b.jpg");

Mat src_gray;

std::vector<cv::Rect> money;

CascadeClassifier euro2_cascade;

cvtColor(src, src_gray, CV_BGR2GRAY );
equalizeHist(src_gray, src_gray);

if ( !euro2_cascade.load( "cascade.xml" ) ) {
    printf("--(!)Error loading\n");
    return -1;
}

euro2_cascade.detectMultiScale( src_gray, money, 1.1, 3, 0|CASCADE_SCALE_IMAGE/*CV_HAAR_FIND_BIGGEST_OBJECT | CV_HAAR_SCALE_IMAGE*/, cv::Size(10, 10),cv::Size(2000, 2000) );
printf("%d\n", int(money.size()));

for( size_t i = 0; i < money.size(); i++ ) {
    cv::Point center( money[i].x + money[i].width*0.5, money[i].y + money[i].height*0.5 );
    ellipse( src, center, cv::Size( money[i].width*0.5, money[i].height*0.5), 0, 0, 360, Scalar( 255, 0, 255 ), 4, 8, 0 );
}

namedWindow( "Display window", WINDOW_AUTOSIZE );
imwrite("result.jpg",src);
}