Repeater隔行显示红色

protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)

        {

            if (e.Item.ItemType == ListItemType.AlternatingItem)

            {

 

                TextBox tb = (TextBox)e.Item.FindControl("TextBox1");

                if (tb.Text.Contains("o"))

                {

                    tb.BackColor = Color.Red; 

                }

            }

        }