When i am adding first row then if else condition is working but when i add second row then if else condition is not working

As per your refer Link

Delete dynamic added GridView Row on Button Click using C# in ASP.Net

        protected void txtamount_TextChanged(object sender, EventArgs e)
        {
            foreach (GridViewRow row in gvtrans.Rows)
            {
                TextBox bankid = row.FindControl("txtcode") as TextBox;

                TextBox locid = row.FindControl("txtbank_id") as TextBox;
                TextBox chqno = row.FindControl("txtChqno") as TextBox;
                TextBox date = row.FindControl("txtdate") as TextBox;
                TextBox amt = row.FindControl("txtamount") as TextBox;

                if (bankid.Text == "")
                {
                    Response.Write("<script>alert('Please Select Bank')</script>");

                }
                else if (locid.Text == "")
                {
                    Response.Write("<script>alert('Please Select Location')</script>");
                }
                else if (chqno.Text == "")
                {
                    Response.Write("<script>alert('Please Input Chequ No.')</script>");
                }
                else if (date.Text == "")
                {
                    Response.Write("<script>alert('Please Select Cheque Date')</script>");
                }
                else if (amt.Text == "")
                {
                    Response.Write("<script>alert('Please Input Amount')</script>");
                }
                else
                {
                    addrow();
                    CalculateTotal();
                }
            }            
        }