I wrote a program try to use the slider to control video play, but when I executed it, I can't see the slider window.what's wrong with my code?

#include<highgui.h>
#include<cv.h>
#include<iostream>

int g_slider_position = 0;
CvCapture *g_capture = NULL;

void onTrackbarSlide(int position)
{
	cvSetCaptureProperty(g_capture, CV_CAP_PROP_POS_FRAMES, position);

	return;
}

int main()
{
	cvNamedWindow("sd", CV_WINDOW_AUTOSIZE);
	g_capture = cvCreateFileCapture("F://迅雷下载/永远的车神.rmvb");
	int frames = (int) cvGetCaptureProperty(g_capture, CV_CAP_PROP_FRAME_COUNT);
	if (frames != 0)
	{
		cvCreateTrackbar("position", "example", &g_slider_position, frames, onTrackbarSlide);
	}
	IplImage *frame;
	frame = cvQueryFrame(g_capture);
	while (frame)
	{
		cvShowImage("sd", frame);
		if (cvWaitKey(33) == 13)
			break;
		frame = cvQueryFrame(g_capture);
	}
	cvReleaseCapture(&g_capture);
	cvDestroyWindow("sd");
	std::cout << "Program end.\n";
	return 0;
}