Image is not loading into Texture

I'm doing vuforia augmented reality app with image recognition. I'm loading image into texture using www but the the url of the image is showing proper and it's not loading and showing as image.

 if(type.Equals("image")){
 
             StartCoroutine (loadImage(url));
 
             mShowGUIButton=true;
 
             Debug.Log("image URL is"+ url);
 }
 
 IEnumerator loadImage(string imageURL) {
 
         WWW www_image = new WWW (imageURL); 
         yield return www_image;
         renderer.material.mainTexture = www_image.texture;
 }