I tried to display first row of GridView empty, but it is not getting display

Referred below link

Add new Row to GridView on Button Click in ASP.Net

Below is html  

<asp:GridView ID="gvtrans" runat="server" AllowSorting="True" AutoGenerateColumns="False" CssClass="active right"
    BorderColor="#E7E7FF" itemstyle-wrap="True" GridLines="Horizontal" ShowHeaderWhenEmpty="True" OnRowDataBound="gvtrans_RowDataBound"
    ShowFooter="True" OnRowCreated="gvtrans_RowCreated" BackColor="White" BorderStyle="None" BorderWidth="1px" 
    CellPadding="3" Style="margin-top: 0px; margin-left: 0px;" Width="824px">    
    <Columns>
        <asp:BoundField DataField="RowNumber" HeaderText="Row Number" />
        <asp:TemplateField HeaderText="Code">
            <ItemTemplate>
                <asp:TextBox ID="txtcode" runat="server"></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Head">
            <ItemTemplate>
                <asp:Label ID="lbfourdr" runat="server" Visible="false" />
                <asp:DropDownList runat="server" AutoPostBack="true" CssClass="form-control js-example-placeholder-single" ID="ddlfourdr"
                    Width="250px" OnSelectedIndexChanged="ddlfourdr_SelectedIndexChanged">
                </asp:DropDownList>
            </ItemTemplate>
        </asp:TemplateField>

        <asp:TemplateField HeaderText="Debit">
            <ItemTemplate>
                <asp:TextBox ID="txtDebit" runat="server" AutoPostBack="true" OnTextChanged="txtDebit_TextChanged"></asp:TextBox>
            </ItemTemplate>
            <FooterTemplate>
                <asp:Label ID="lblTotal" runat="server"></asp:Label>
            </FooterTemplate>

        </asp:TemplateField>
        <asp:TemplateField HeaderText="Credit">
            <ItemTemplate>
                <asp:TextBox ID="txtCredit" runat="server" AutoPostBack="true" OnTextChanged="txtCredit_TextChanged"></asp:TextBox>
            </ItemTemplate>
            <FooterTemplate>
                <asp:Label ID="lblTotalcr" runat="server"></asp:Label>
            </FooterTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Type">
            <ItemTemplate>
                <asp:DropDownList ID="ddltype" runat="server" Width="70px">
                    <asp:ListItem Text="Credit" Value="1"></asp:ListItem>
                    <asp:ListItem Text="Debit" Value="2"></asp:ListItem>
                </asp:DropDownList>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

protected void Page_Load(object sender, EventArgs e)
{

    if (!Page.IsPostBack)
    {
        SetInitialRow();
    }
}

private void SetInitialRow()
{
    dt.Columns.Add(new DataColumn("RowNumber", typeof(string)));
    dt.Columns.Add(new DataColumn("txtcode", typeof(string)));
    dt.Columns.Add(new DataColumn("ddlfourdr", typeof(string)));
    dt.Columns.Add(new DataColumn("txtDebit", typeof(string)));
    dt.Columns.Add(new DataColumn("txtCredit", typeof(string)));
    dt.Columns.Add(new DataColumn("ddltype", typeof(string)));
    dr = dt.NewRow();
    dr["RowNumber"] = 1;
    dr["txtcode"] = string.Empty;
    dr["txtDebit"] = string.Empty;

    dr["txtCredit"] = string.Empty;
    //dr = dt.NewRow();
    //Store the DataTable in ViewState
    ViewState["CurrentTable"] = dt;
    gvtrans.DataSource = dt;
    gvtrans.DataBind();
}