using a custom haar cascade classifier - opencv

Question

I have created a haar cascade classifier for detecting a hand with 1000 positive images and 2000 negative images. The xml file was created using convert_cascade.c from opencv samples. Now I am using the following code for detection, but the assert statement is giving an error as shown below
"assertion failed= cascade && storage && capture, line 21", which is the assertion call itself. I know that assertion fails when the expression evaluates to zero. so, any idea what could be wrong with classifier, because storage and capture should be working fine anyways,
#include <stdio.h>
#include "opencv/cv.h"
#include "opencv/highgui.h"
CvHaarClassifierCascade *cascade;
CvMemStorage *storage;
void detect( IplImage *img );
int main( )
{
CvCapture *capture;
IplImage *frame;
int key;
char *filename = "haar3.xml"; // name of my classifier
cascade = ( CvHaarClassifierCascade* )cvLoad( filename, 0, 0, 0 );
storage = cvCreateMemStorage(0);
capture = cvCaptureFromCAM(0);
assert( cascade && storage && capture );
cvNamedWindow("video", 1);
while(1) {
frame = cvQueryFrame( capture );
detect(frame);
key = cvWaitKey(50);
}
cvReleaseImage(&frame);
cvReleaseCapture(&capture);
cvDestroyWindow("video");
cvReleaseHaarClassifierCascade(&cascade);
cvReleaseMemStorage(&storage);
return 0;
}
void detect(IplImage *img)
{
int i;
CvSeq *object = cvHaarDetectObjects(
img,
cascade,
storage,
1.5, //-------------------SCALE FACTOR
2,//------------------MIN NEIGHBOURS
1,//----------------------
// CV_HAAR_DO_CANNY_PRUNING,
cvSize( 24,24), // ------MINSIZE
cvSize(640,480) );//---------MAXSIZE
for( i = 0 ; i < ( object ? object->total : 0 ) ; i++ )
{
CvRect *r = ( CvRect* )cvGetSeqElem( object, i );
cvRectangle( img,
cvPoint( r->x, r->y ),
cvPoint( r->x + r->width, r->y + r->height ),
CV_RGB( 255, 0, 0 ), 2, 8, 0 );
//printf("%d,%d\nnumber =%d\n",r->x,r->y,object->total);
}
cvShowImage( "video", img );
}