Unable to cast a dropdownlist in GridView and Convertible

Question

Greeting all

I have a gridView as photo below

 

A position dropdownlist connect alone with (SQLDATASOURC) to get Brunch name and Id and implement them to Dropdownlist......Anyway..when I select any item from dropdownlist showing that mistake

 

Unable to cast object of type 'System.Web.UI.WebControls.DropDownList' to type 'System.IConvertible'.

as photo beow:

 

 I used many many many solutions to resolve that no way..

Have anyone a perfect way to resolve that mistake..

Take a view a bout code below:

protected void gvjobsshow_RowUpdating(object sender, GridViewUpdateEventArgs e)
        {
            try
            {
                using (SqlConnection sqlcon = new SqlConnection(connectionString))
                {

                    sqlcon.Open();
                      string query = "UPDATE Jobs SET Job_title = @Job_title, Job_desc = @Job_desc,P_date = @P_date, C_date = @C_date,Branch_Id = @Branch_Id, JType_Id = @JType_Id, JEnable = @JEnable WHERE (Jobs.Id = @Id)";

                    string Pday = ((TextBox)gvjobsshow.Rows[e.RowIndex].FindControl("TB_PDate")).Text;
                    string Cday = ((TextBox)gvjobsshow.Rows[e.RowIndex].FindControl("TBCdate_E")).Text;
                    //====That solution to get DropDownlist value and imlement it is Variable, and then implement a variable in SQL Upadate=====
                    DropDownList DDLBrID1 = (DropDownList)gvjobsshow.Rows[e.RowIndex].FindControl("DDl_Po_E");
                    string DDLBrID2 = DDLBrID1.SelectedItem.Value.ToString();

                    SqlCommand sqlcmd = new SqlCommand(query, sqlcon);
                    sqlcmd.Parameters.AddWithValue("@Job_title", (gvjobsshow.Rows[e.RowIndex].FindControl("TB_Tit_E") as TextBox).Text.Trim());
                    sqlcmd.Parameters.AddWithValue("@Job_desc", (gvjobsshow.Rows[e.RowIndex].FindControl("TbDes_E") as TextBox).Text.Trim());
                    sqlcmd.Parameters.AddWithValue("@P_date", Pday);
                    sqlcmd.Parameters.AddWithValue("@C_date", Cday);
                    sqlcmd.Parameters.AddWithValue("@Branch_Id", DDLBrID2);

                    //sqlcmd.Parameters.Add("@Branch_Id", SqlDbType.Int).Value = ((DropDownList)gvjobsshow.Rows[e.RowIndex].FindControl("DDl_Po_E"));

                    //==== I used that solution to access to dropdownlist value and return it with [[Convert.ToInt32]] but no way...
                    //sqlcmd.Parameters.AddWithValue("@Branch_Id", Convert.ToInt32((gvjobsshow.Rows[e.RowIndex].FindControl("DDl_Po_E"))));
                    sqlcmd.Parameters.AddWithValue("@JType_Id", Convert.ToInt32((gvjobsshow.Rows[e.RowIndex].FindControl("DDl_Miss_E"))));
                    sqlcmd.Parameters.AddWithValue("@JEnable", Convert.ToBoolean((gvjobsshow.Rows[e.RowIndex].FindControl("Ch_E") as CheckBox).Checked));
                    sqlcmd.Parameters.AddWithValue("@Id", Convert.ToInt32(gvjobsshow.DataKeys[e.RowIndex].Value.ToString()));
                    sqlcmd.ExecuteNonQuery();
                    gvjobsshow.EditIndex = -1;
                    GVShowJobs();
                    JobSuUp.Text = "Selected Record has been Updated.";

                }
            }
            catch (Exception ex)
            {

                JobFaUp.Text = ex.Message;
            }
        }