show/hide modalpopup inside Gridview/Repeater based on condition

inside ItemTemplate
<asp:HyperLink ID="hpldwn" CssClass="Details" runat="server" NavigateUrl="" Text='<%# DataBinder.Eval(Container.DataItem, "worksheetfilename")%>'>
<cc1:ModalPopupExtender ID="ModalPopupExtender1" runat="server"
    BackgroundCssClass="ModalBackground" CancelControlID="btnCancel" TargetControlID="hpldwn" PopupControlID="panOpen" 
    PopupDragHandleControlID="panOpen" Enabled="false"> </cc1:ModalPopupExtender>

Inside ItemDataBound Event of Repeater

           HyperLink Link = (HyperLink)e.Item.FindControl("hpldwn");
            string fname = "http://sisonline.in/Worksheet/" + (Session["SchoolId"]).ToString() + "/" + Link.Text;
            string filepath = "Worksheet/" + (Session["SchoolId"]).ToString() + "/" + Link.Text;
            bool available = File.Exists(Server.MapPath(filepath));
            if (available)
            {              
                Link.ForeColor = System.Drawing.Color.Blue;
                HtmlGenericControl control = (HtmlGenericControl)e.Item.FindControl("Frame1");               
                control.Attributes["src"] = fname;
                ModalPopupExtender modal = (ModalPopupExtender)e.Item.FindControl("ModalPopupExtender1");
                modal.Enabled = true;
                Link.Attributes["style"] = "cursor:pointer";
            }
            else
            {             
                Link.Text = "This File has been Removed from Server";
                Link.ForeColor = System.Drawing.Color.Red;
                Link.Style.Add("text-decoration", "none");
            }