Camera Interfacing with Opencv: - c++

Question

I have Windows 8 on "DELL Inspiron 5537" installed and i create a virtual machine from "Virtual box" and installed Ubuntu 13.04 in it. And then I installed Opencv Version=2.4.9 through commands in Ubuntu's terminal now I want to do camera interfacing in opencv which is very necessary for my project to move forward..my code contains no error still it is not working the way i want.
My code is given below:
#include <iostream>
#include <cv.h>
#include <highgui.h>
using namespace std;
char key;
int main()
{
cvNamedWindow("Camera_Output", 1); //Create window
CvCapture* capture = cvCaptureFromCAM(CV_CAP_ANY);
//Capture using any camera connected to your system
while(1){ //Create infinte loop for live streaming
IplImage* frame = cvQueryFrame(capture); //Create image
frames from capture
cvShowImage("Camera_Output", frame); //Show image
frames on created window
key = cvWaitKey(10); //Capture Keyboard stroke
if (char(key) == 27){
//cvSaveImage("webcam_frame.png",frame);
}
}
cvReleaseCapture(&capture); //Release capture.
cvDestroyWindow("Camera_Output"); //Destroy Window
return 0;
}
when I run this code in my terminal it is not capturing the image rather it shows a blank window. I have attached a photo of output of this code.