dropdownlist的value取值,该怎么解决

 private void AddUserDepNameBind()    {        BLL.Accounts_Department bll = new BLL.Accounts_Department();        DataSet ds = bll.GetAllList();        this.AddUserDepName.DataSource = ds.Tables[0];        this.AddUserDepName.DataTextField = "DepName";        this.AddUserDepName.DataValueField = "DepartmentID";        this.AddUserDepName.DataBind();                    }

 protected void SaveInfomation_Click(object sender, EventArgs e)    {                string strError = "";        if (this.AddUserName.Text.Trim().Length==0)        {            strError += "用户名不能为空！\\n";        }        if (this.AddUserPwd.Text.Trim().Length==0)        {            strError += "密码不能为空\\n";        }        if (this.AddTrueName.Text.Trim().Length==0)        {            strError += "真实姓名不能为空\\n";        }        if (!PageValidate.IsNumber(AddUserAge.Text))        {            strError += "年龄格式错误\\n";        }        if (!PageValidate.IsDateTime(AddUserbirthday.Text))        {            strError += "出生日期格式错误\\n";        }        if (this.AddUserPhone.Text.Trim().Length==0)        {            strError += "电话号码不能为空\\n";        }                if (this.AddUserEmail.Text.Trim().Length==0)        {            strError += "E-Mail不能为空\\n";        }        /*string EmailRegex=@"^[/w-]+(/.[/w-]+*@[/w-]+(/.[/w=]+)+$";        if (Regex.IsMatch(AddUserEmail.Text,EmailRegex))        {            Response.Write("<script>alt"+"邮箱格式错误"+"</script>");        }*/        if (strError!="")        {            MessageBox.Show(this.Page,strError);                       return;                  }       // BLL.Accounts_Department Depbll = new BLL.Accounts_Department();        //定义以及初始化        string UserName = this.AddUserName.Text;        //byte[] UserPassword = new UnicodeEncoding().GetBytes(this.AddUserPwd.Text);        byte[] UserPassword = EncryptPassword(this.AddUserPwd.Text);        string TrueName = this.AddTrueName.Text;        string Sex = this.AddUserSex.SelectedValue.ToString();        int Age = int.Parse(this.AddUserAge.Text);        DateTime BirthDay = DateTime.Parse(this.AddUserbirthday.Text);        string Phone = this.AddUserPhone.Text;        string Email = this.AddUserEmail.Text;        //int DepName = this.AddUserDepName.SelectedIndex;        //int DepName = Convert.ToInt32(this.AddUserDepName.Items[0].Value);               //int DepName =Convert.ToInt32( Depbll.GetID(this.AddUserDepName.Text));        //int DepName =Convert.ToInt32( this.AddUserDepName.DataValueField);        //int DepName =Convert.ToInt32( this.AddUserDepName.SelectedItem.Value);        int DepName =Convert.ToInt32( this.AddUserDepName.SelectedValue);        //int DepName = AddUserDepName_SelectedIndexChanged(DepName);        string UserType = this.AddUserType.SelectedValue.ToString();        //赋值        Model.Accounts_Users model = new Model.Accounts_Users();        model.UserName = UserName;        model.UserPassWord = UserPassword;        model.TrueName = TrueName;        model.Sex = Sex;        model.Age = Age;        model.BirthDay = BirthDay;        model.Phone = Phone;        model.Email = Email;        model.DepartmentID = DepName;        model.UserType = UserType;        //业务逻辑层处理        BLL.Accounts_Users bll = new BLL.Accounts_Users();        bll.Add(model);        Common.MessageBox.ShowAndRedirect(this.Page, "保存成功！", "User.aspx");    }

protected void Page_Load(object sender, EventArgs e)    {        AddUserDepNameBind();        AddUserTypeBind();               if (!IsPostBack)        {            //AddUserDepNameBind();            //AddUserTypeBind();        }    }