OnSelectedIndexChanged event won't fire for the first element of DropDownList

[Maestro]

I have a \[code\]DropDownList\[/code\] and the method for \[code\]OnSelectedIndexChanged\[/code\] event changes the content of one label. It works fine except for the first element of the \[code\]DropDownList\[/code\]. Any ideas?\[code\]using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using Newsletter.DAL;using Newsletter.Services;public partial class Senders : System.Web.UI.Page{ private SenderService _client; private List<Sender> _allSenders; private DropDownList _dropDownListSenders; private TextBox _emailBox; private string _selectedSender; protected void Page_Load(object sender, EventArgs e) { _client = new SenderService(); _allSenders = _client.GetAllSenders(); _dropDownListSenders = (DropDownList)loginViewMain.FindControl("DropDownListSenders"); _emailBox = (TextBox)loginViewMain.FindControl("textBoxEmail"); } protected void DropDownListSenders_SelectedIndexChanged(object sender, EventArgs e) { _selectedSender = _dropDownListSenders.SelectedValue; _emailBox.Text = _selectedSender; }}\[/code\]