listbox绑定数据源以后选中失效

做了一个网站，两个Listbox 数据互转listbox1的数据是直接加载的往listbox2中添加时选中无效代码如下             protected void Button3_Click(object sender, EventArgs e)
             { 
                 int count = ListBox1.Items.Count;
                 int index = 0;                 
                 for (int i = 0; i < count; i++)
                 {
                     ListItem newitem = ListBox1.Items[index];
                     if (ListBox1.Items[index].Selected == true)
                     {  ListBox1.Items.Remove(newitem); ListBox2.Items.Add(newitem); }                                                                                 
                     else { index++; }                    
                 }                     
             }ListBox1.Items[index].Selected == true  判断似乎不起作用数据绑定的部分是：                        .......................................省略部分                SqlDataAdapter da = new SqlDataAdapter(mycom);
             DataTable newtable = new DataTable();
             da.Fill(newtable);
             ListBox1.DataSource = newtable;
             ListBox1.DataBind();
             mycon.Close();希望高手指教