Response.Redirect

Hi ..
I have a problem with  Response.Redirect to specific error page.
so far i have something like :
 protected void Page_Load(object sender, EventArgs e)
    {

  if ((Request.QueryString["UbytovaniePrispevokID"].ToString()) == "")
        {
           Response.Redirect("DefaultError.aspx");
        }
    }
What i want to do is.. I have one main page with new posts Each subject of the new post is the link to Another page where is Specific post and coments and user can leave a coment.
What I want is when the Request.QueryString["UbytovaniePrispevokID"].ToString()) == "" or null I want to redirect to error page ...
 
Thanks
...