Selected Listbox Items Into Database

How can i get ALL the selected items into the database? this loop only accepts one item. I have tried with a "clear" action, does not work....
 
   protected void Button2_Click(object sender, EventArgs e)
       {
           if (Page.IsValid)
               {
               // Define data objects
                   SqlConnection conn;
                   SqlCommand comm;
  
               // Open the connection
                   string connectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
              
               // Initialize connection
                   conn = new SqlConnection(connectionString);
  
               // Create command
               comm = new SqlCommand("INSERT INTO TestTabel (TestNavn) VALUES (@TestNavn)",conn);
               // Add command parameters

              
               foreach (ListItem item in TestListBox.Items)
               {
                   if (item.Selected)
                   {
                       comm.Parameters.Add("@TestNavn", System.Data.SqlDbType.NVarChar);
                       comm.Parameters["@TestNavn"].Value = Item.Text;
                   }
               }


               // Enclose database code in Try-Catch-Finally
               try
                   {
                   // Open the connection
                   conn.Open();
                   // Execute the command
                   comm.ExecuteNonQuery();
                   // Reload page if the query executed successfully
                   Response.Redirect("Default.aspx");
                   }
               catch(Exception Arg)
                   {
                    Response.Write(Arg.Message);   
                    // Display error message
                    Label1.Text = "Error !";
                   }
               finally
                   {
                   // Close the connection
                   conn.Close();
                   }
               }
          }