GridView Row Coloring based upon condition in ASP.net

<asp:DataGrid ID="gd" runat="server"
AutoGenerateColumns="False" BorderColor="Black"
BorderStyle="Solid" BorderWidth="1px" CellPadding="2"
CssClass="ArialNarrow"GridLines="Vertical" Width="100%"
OnItemDataBound="gd_ItemDataBound" AllowPaging="True"
onpageindexchanged="gd_PageIndexChanged" PageSize="50" >


< PagerStyle HorizontalAlign="center" Mode="NumericPages"
PageButtonCount="10"/>
< SelectedItemStyle BackColor="White"
ForeColor="White" />
< AlternatingItemStyle BackColor="AliceBlue" HorizontalAlign="Left" />
< ItemStyle BackColor="White" ForeColor="Black" HorizontalAlign="Left" VerticalAlign="Top" />
< HeaderStyle HorizontalAlign="Center" VerticalAlign="Top" BackColor="#000084" ForeColor="White" Font-Bold="True" />  

< Columns >
     < asp:TemplateColumn  ItemStyle-Wrap="false" >
         < ItemTemplate >
            < asp:Label ID="lblNo" runat="server" Text='<%# Eval( "No") %>' />
            < asp:Label ID="lblDra" Visible="false" runat="server" Text='<%# Eval("Id") %>' />
         < /ItemTemplate >
    < /asp:TemplateColumn >

    < asp:TemplateColumn  >
        < ItemTemplate >
           < asp:Label ID="lblFun" runat="server" Text='<%# Eval( "Fun") %>' />
        </ItemTemplate>
    </asp:TemplateColumn>

    < asp:TemplateColumn HeaderText="Desc" >
       < ItemTemplate >
          < asp:Label ID="lblDesc" runat="server" Text='<%# Eval( "Desc") %>' />
       </ItemTemplate>
   </asp:TemplateColumn> 

   < asp:TemplateColumn  >
     < ItemTemplate >
        < asp:Label ID="lblApp" runat="server" Text='<%# Eval( "App_Date","{0:dd-MMM-yyyy}") %>' Visible="false" / >
        < asp:Label ID="lblRev" runat="server" Text='<%#Eval("Rev_No") %>'/>
     < /ItemTemplate >
   < /asp:TemplateColumn >
                    
   < asp:TemplateColumn  >
     < ItemTemplate >
         < asp:Label ID="lblSze" runat="server" Text='<%# Eval( "Size_Desc") %>'/>
     </ItemTemplate>
   </asp:TemplateColumn>
                     
   <asp:TemplateColumn>
      < ItemTemplate >
        < asp:LinkButton ID="btnEdit" CommandName="Edit" runat="server" Text="Upload" CausesValidation="false" />
      </ItemTemplate>
   </asp:TemplateColumn>                                               
                      
  </Columns>
</asp:DataGrid>

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Utilities;
using Microsoft.SharePoint.Workflow;
using Microsoft.SharePoint.WebControls;
using System.Diagnostics;
 // using this i'm calling dll's
 // using this i'm calling my webreference

public partial class Resource1 : System.Web.UI.Page
{
    string Web_Login;
    double UserId;
    string Code;
    int C_Code = 0;



    protected void Page_Load(object sender, EventArgs e)
    {
        lntSPCurrentSite objCurrentSite = new lntSPCurrentSite();
        lntSPCurrentUser objCurrentUser = new lntSPCurrentUser();
        Design objDesign = new Design();

        Web_Login = objCurrentUser.LoginName;
        UserId = objDesign.UserId_WebLogin(Web_Login);

        Code = objCurrentSite.WebSiteName;

        if (!IsPostBack)
        {           
            Document();
        }
    }
    
    //Bind GridView Data
    protected void Document()
    {
        Design objDocument = new Design();
        DataSet dsDocument = new DataSet();
        
        dsDocument = //fetch data;        
        ViewState["dsDocument"] = dsDocument;
        gd.DataSource = dsDocument;
        gd.DataBind();
    }
   
    protected void gd_ItemDataBound(object sender, DataGridItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            //File uploaded date
            string App_Date = ((Label)e.Item.FindControl("lblApp")).Text;
            string Id = ((Label)e.Item.FindControl("lblDwg")).Text;
            string Rev = ((Label)e.Item.FindControl("lblRev")).Text;
           
            DataTable dtDwg = (ViewState["dsDocument"] as DataSet).Tables[0];

            //Here i'm checking the Uploaded Dwg's Status

            DataRow[] drow = dtDrawing.Select("Id=" + Id + " AND OutCome='000006'");

            if (App_Date != "")
            {
                //Here i'm fetching file uploaded date
                DateTime x = Convert.ToDateTime(((Label)e.Item.FindControl("lblApp")).Text);

                // Here i'm fecthing System Date.
                DateTime y = DateTime.Now.Date;

                //taking the difference between 2 dates
                int z = Convert.ToInt32((y - x).TotalDays);


                //Dwg is upload it's comes to else part
                if (drow != null && drow.Length == 0)
                {
                    // difference is in betweem 0 to 15 days then show the color yellow
                    if (z >= 0 && z < 15)
                    {
                        e.Item.BackColor = System.Drawing.Color.LightYellow;

                    }

                    //dfference is less than 0, then Gainsboro color.
                    else if (z < 0)
                    {

                        e.Item.BackColor = System.Drawing.Color.Gainsboro;

                    }
                   
                    else
                        e.Item.BackColor = System.Drawing.Color.LightSalmon;
                }

                // Dwg already uploaded then Green Color
                else
                {
                    e.Item.BackColor = System.Drawing.Color.PaleGreen;
                }
            }
        }
    }
   

    //Apply paging to the GridView...

    protected void gd_PageIndexChanged(object source, DataGridPageChangedEventArgs e)
    {
        gd.CurrentPageIndex = e.NewPageIndex;
        Document();
    }   
}