selected datarow from datalist is not getting assigned to datatable columns

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C#

ASP.NET

In the following code I select a row from datalist using 'add to cart' button event.
I want to pass certain columns to a datatable as a new row and later bind into a gridview.
It works without error or exception but the values are not getting assigned to respective TextBox's and with respective columns of the datatable. Can any one help me out. I am struck here.

<asp:DataList ID="DataList1" runat="server"  RepeatColumns="2" OnItemCommand="dl_item_command"   RepeatDirection="Horizontal"  >
    <ItemTemplate>
    <table id="Table1" cellpadding="1" cellspacing="1" visible ="true">
    <tr>
    <td width="140px">
    <p align="left">
    <b>Product ID: </b>
    <asp:Label ID="lblEmpCode" runat ="server"
    Text= '<%#DataBinder.Eval(Container.DataItem, "product_id")%>'>
    </asp:Label>
    </p>
    </td>
    </tr>
    </table>
    <table id="Table2" style=" margin-top:-33px" cellpadding="1" cellspacing="1" visible ="true">
    <tr>
    <td>
    <td  style="left:0px"width="200px">
    <p align="left">
    <b>Product Name: </b>
    <asp:Label ID="lblEmpName" runat = "server"
    Text=' <%# DataBinder.Eval(Container.DataItem, "product_name")%>'>
    </asp:Label>
    </p>
    </td>
    </tr>
    </table>
    <table id="Table6" cellpadding="1" style=" margin-top:-39px" cellspacing="1"  width="360px" visible ="true">
    <tr>
    <td >
    <p align="left">
    <asp:TextBox ID="AddToCartTB"  runat = "server" Text='1' Width="44px"> </asp:TextBox>

    <asp:Button ID="AddToCart"  runat = "server" Text='Add to Cart' Width="100px" commandname="myevent">
    </asp:Button>
    </p>
    </td>
    </tr>
    </table>
    </ItemTemplate>
</asp:DataList>

private void AddNewRow()
    {
        int rowIndex = 0;
        if (ViewState["CurrentTable"] != null)
        {
            DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
            DataRow drCurrentRow = null;
            if (dtCurrentTable.Rows.Count > 0)
            {
                for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
                {
                    TextBox TB_Productid =
                      (TextBox)grvcart.Rows[rowIndex].Cells[2].FindControl("TBProductId");
                    TextBox TB_ProductName =
                      (TextBox)grvcart.Rows[rowIndex].Cells[3].FindControl("TBProductName");
                    drCurrentRow = dtCurrentTable.NewRow();
                    drCurrentRow["RowNumber"] = i + 1;
                    dtCurrentTable.Rows[i - 1]["Col1"] = TB_Productid.Text;
                    dtCurrentTable.Rows[i - 1]["Col2"] = TB_ProductName.Text;
                    rowIndex++;
                }
                dtCurrentTable.Rows.Add(drCurrentRow);
                ViewState["CurrentTable"] = dtCurrentTable;
                grvcart.DataSource = dtCurrentTable;
                grvcart.DataBind();
            }
        }
        else
        {
            Response.Write("ViewState is null");
        }
        SetPreviousData();
    }