cant bind data from sql server 2008 r2 to gridview through vs2010

Question

Hi


i have a requirement , i want to display the users in a webpart.

i have done some coding but it is not working.

i want to display the data from sql server table to a grid view in vs2010 through a web part

my code is

protected void Button1_Click(object sender, EventArgs e)
        {
            SqlCommand cmd;
            SqlDataAdapter da;
            DataSet ds = new DataSet();
            SqlConnection con = new SqlConnection("Data Source=spsrv;Initial Catalog=GrandCacheCodeDB;User Id=sa;Password=Pass1234;Integrated Security=True");

            con.Open();
            string str = ("select UserId,UserName from aspnet_Users ");
            cmd = new SqlCommand(str, con);
            da = new SqlDataAdapter(cmd);
            da.Fill(ds, "aspnet_Users");
            gv.DataSource = ds.Tables[0];
            gv.DataBind();
            con.Close();
        }
                }
            }


the data is not geting binded to the gridview can u halp me out