How to get user's profile picture with Facebook's Unity SDK?

I'm trying to get the profile pic of the user of the game using this-

void MyPictureCallback(FBResult result) // store user profile pic
{
        if (FB.IsLoggedIn)
        {
            WWW url = new WWW("http" + "://graph.facebook.com/" + FB.UserId + "/picture");

            Texture2D textFb2 = new Texture2D(128, 128, TextureFormat.ARGB32, false); //TextureFormat must be DXT5

            url.LoadImageIntoTexture(textFb2);
            profilePic.renderer.material.mainTexture = textFb2;
        }

But it isn't working. I am getting no errors.

I fixed it with this-

WWW url = new WWW("https" + "://graph.facebook.com/" + userId + "/picture?type=large"); //+ "?access_token=" + FB.AccessToken);

            Texture2D textFb2 = new Texture2D(128, 128, TextureFormat.DXT1, false); //TextureFormat must be DXT5

            yield return url;
            profilePic.renderer.material.mainTexture = textFb2;
            url.LoadImageIntoTexture(textFb2);
            Debug.Log("Working");