ASP.MVC return image doesn't work in BBCODE

i have some simple code

public virtual ActionResult Get(int id)
{
    using (var db = new ImagesEntities())
    {
        var b = db.Images.SingleOrDefault(bo => bo.Id == id);
        return File("C:\\images\\" + b.FileName, "image/jpeg");
    }
}

It works in html for example < img src开发者_高级运维="http://mysite.com/mycontroler/Get/1" />

but on some forums with BBCode it doesnt work and returns plain text instead of image

any help?

Url must ends with '.jpg', '.png' etc....