Update panel refreshes page instead of gridview while paging

how can i use trigger here ? if i use trigger then i need to keep gridview outside the update panel. sp then what will be in update panel

                              
                                  
                                                                    AutoGenerateColumns="false" AllowPaging="True" PageSize="10"
                                    onpageindexchanging="GridView1_PageIndexChanging"
                                    onrowdatabound="GridView1_RowDataBound" AllowSorting="True" OnPreRender="GridView1_PreRender"
                                    BorderStyle="None">
                                   
                               
                       
                               
                               
                      
                               
                                
                                 
                                     
                                                                                             href='<%#String.Format("http://bseindia.com/stockinfo/anncomp.aspx?scripcode={0}", Eval("BSECode"))%>'>
                                                 
                                                       <%#Eval("CoName") %>-                                                             Text="">
                                               
                                                                                                            Value='<%#Eval("Name") %>' />
                                                   
                                               
                                           
                                            <%#Eval("PublishDate", "{0:hh:mm tt}")%>
                                       
                     
                       
                       
                       
                       
                  
                    
                         
======================Code behind=================================

 protected void Page_Load(object sender, EventArgs e)
    {       
        if (!Page.IsPostBack)
        {
            GridView1.PageIndex = 0;
         
            object[] param = new object[2];

        param[0] = "HomePageAnnouncement";
        param[1] = DBNull.Value;

        GridView1.DataSource = objHandler.ExecuteProcedureRtnDT("RB_CompanyAnnouncement", param);
        GridView1.DataBind();
        }
    }


 protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
      
        GridView1.PageIndex = e.NewPageIndex;
      
        lstComAnn();
        UPCompanyAnnonce.Update();
    }


 private string prevEventDateAnnouncement1 = "00 xxx 0000";
    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            string AnnouncementDate = string.Empty;

            AnnouncementDate = Convert.ToDateTime(GridView1.DataKeys[e.Row.RowIndex].Value).ToString("dd MMM yyyy");

         

            if (!prevEventDateAnnouncement1.Equals(AnnouncementDate, StringComparison.CurrentCultureIgnoreCase))
            {
             
                HtmlTableRow trDate = (HtmlTableRow)e.Row.FindControl("trDate");
                HtmlTableCell htc = new HtmlTableCell();
                htc.ColSpan = 2;
                htc.Attributes.Add("class", "date-hd");
                htc.InnerHtml = "" + AnnouncementDate + "";
                trDate.Controls.Add((HtmlTableCell)htc);
                trDate.Visible = true;
                prevEventDateAnnouncement1 = AnnouncementDate;
            }
            HiddenField hdNamenDesignation = (HiddenField)e.Row.FindControl("hdnNamenDesignation");
            HiddenField hdDescription = (HiddenField)e.Row.FindControl("hdnDescription");
            Label lblNamenDesignation = (Label)e.Row.FindControl("lblNamenDesignation");
            Label lblCompanyAnn = (Label)e.Row.FindControl("lblCompanyAnn");

            if (!string.IsNullOrEmpty(hdNamenDesignation.Value))
            {
                lblNamenDesignation.Text = hdNamenDesignation.Value;

                lblCompanyAnn.Attributes.Add("onmouseover", "javascript:tooltip.show('" + hdDescription.Value.Replace("'", "") + "');");
                lblCompanyAnn.Attributes.Add("onmouseout", "javascript:tooltip.hide();");
            }
            else
            {
                if (hdDescription.Value.Length > 31)
                {
                    lblNamenDesignation.Text = hdDescription.Value.Substring(0, 30) + "...";

                    lblCompanyAnn.Attributes.Add("onmouseover", "javascript:tooltip.show('" + hdDescription.Value.Replace("'", "") + "');");
                    lblCompanyAnn.Attributes.Add("onmouseout", "javascript:tooltip.hide();");
                }

            }
        }

    }

yes it is inside ispostback method

In Page_Load() Event, Check Whether isPostBack or not like,


 protected void Page_Load(object sender, EventArgs e)    {
        if (!IsPostBack)
        {
             // Your Taks on when Page gets Loaded.
        }
    }