Draw image in another image doesn't work on iOS device
===

I need your help to draw an image in another image on iOS. For this moment, I use the code below:

    UIImage* finalimage = [self drawImage:ECAImage inImage:finalimage atPoint:ECALocation]; 

My function:

    -(UIImage*) drawImage:(UIImage*) fgImage inImage:(UIImage*) bgImage atPoint:(CGPoint)  point
    {
        UIGraphicsBeginImageContextWithOptions(bgImage.size, FALSE, 0.0);
        [bgImage drawInRect:CGRectMake( 0, 0, bgImage.size.width, bgImage.size.height)];
        [fgImage drawInRect:CGRectMake( point.x, point.y, fgImage.size.width, fgImage.size.height)];
        UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        
        return newImage;
    }

This code works on iPhone 5.0 simulator but not on my device iPhone 5.0.1.
I can display the bgImage but the fgImage is not drawing. Any ideas ?