How to open pdf file new tab in browser in ASP.NET C#

Question

When select an item from dropdownlist it will open a file in new tab. There is no error. but when I click on link button,click event does not fire of link button.

 

Again dropdownlist SelectedIndexChanged event is fired when I click on link button.

 

When I select from dropdownlist , it open a file new tab but dows call javascript function "ResetTarget()"

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<asp:Content ID="BodyContent" ContentPlaceHolderID="MainContent" runat="server">
<script type="text/javascript">
function ResetTarget()
{
alert('Yes');
document.forms[0].target = '';
}
function SetTarget()
{
document.forms[0].target = "_blank";
window.setTimeout("document.forms[0].target='';", 500);
}
</script>
<asp:HiddenField ID="hidCSRF" runat="server" Value="" />
<table align="center" class="SubFormWOBG" style="line-height: 25px; width: 100%">
<tr>
<td style="width: 40%">Application Code: </td>
<td style="width: 60%">
<asp:LinkButton ID="lnkApplicationCode" runat="server" CausesValidation="false" OnClick="lnkApplicationCode_click"></asp:LinkButton>
</td> </tr>
<tr runat="server" id="MandatAtt">
<td>Mandatory Attchment:</td>
<td>
<asp:DropDownList runat="server" ID="ddlAttachment" AutoPostBack="true" OnSelectedIndexChanged="ddlAttachment_SelectedIndexChanged"> </asp:DropDownList>
</td>
</tr>
</table>
</asp:Content>

in c# file

protected void Page_Load(object sender, EventArgs e) {
  if (!IsPostBack) {
    try {
      lnkApplicationCode.Text = "135";
      MandatAtt.Visible = false;
      ddlAttachment.Attributes["onchange"] = "SetTarget();";
      MandatAtt.Visible = true;
    } catch(Exception) {
      Response.Redirect("~/ErrorPage.aspx", false);
    } finally {}
  }
}
protected void ddlAttachment_SelectedIndexChanged(object sender, EventArgs e) {
  try {
    string[] arr = ddlAttachment.SelectedValue.ToString().Split(',');
    int int_attachmentCode = Convert.ToInt32(arr[0]);
    int int_attachmentSerialCode = Convert.ToInt32(arr[1]);
    NOCAPInternalUtility.INDAppViewFiles(Convert.ToInt64(lnkApplicationCode.Text.Trim()), int_attachmentCode, int_attachmentSerialCode);
  } catch(System.Threading.ThreadAbortException ex) {} catch(Exception) {
    Response.Redirect("~/ErrorPage.aspx", false);
  } finally {
    hidCSRF.Value = Convert.ToString(System.Guid.NewGuid());
    ViewState["CSRF"] = hidCSRF.Value;
    ScriptManager.RegisterStartupScript(this, GetType(), "function", "ResetTarget();", false);
  }
}
protected void lnkApplicationCode_click(object sender, EventArgs e) {
  hidCSRF.Value = Convert.ToString(System.Guid.NewGuid());
  ViewState["CSRF"] = hidCSRF.Value;
  try {
    long ApplicationCode = Convert.ToInt64(lnkApplicationCode.Text);
    Session["ApplicationCode"] = ApplicationCode;
  } catch(Exception) {
    Response.Redirect("~/ErrorPage.aspx", false);
  }
}