Populate sql data value to text box in asp .net?

Hi,

I have a text box named txtItemID. An Sql data base table named Item is used. It has the column named ItemID, which is created by using max(ItemID)+1 value. My requirement is whenever the page load occurs(run my page in asp .net), the max(ItemID)+1 value should be shown in the text box txtItemID. I have done these codes but it doesn't works :

private void BindItemID()

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["mydb"].ConnectionString);

con.Open();

SqlCommand cmd = new SqlCommand("Select ItemID from Item", con);

SqlDataAdapter da = new SqlDataAdapter(cmd);

DataTable dt = new DataTable();

da.Fill(dt);

txtItemID.Text = dt.ToString();

txtCode.DataBind();