Export to PDF - filename is always coming back as "undefined"

I am using version 2016.1.225.40 of your asp.net for ajax controls.

I'm using ClientExportManager to export a PDF of a section of a page (a radgrid with page breaks).

It is exporting correctly, but when the browser gets the file, the filename is coming up as "undefined".

I've tried various things; nothing is working. The telerik tags and javascript are below.

I've tried it without the PdfSettings section in the clientexportmanager.

<telerik:RadClientExportManager  ID="PDFExportManager" runat="server" OnClientPdfExported="onClientPdfExported">

    <PdfSettings FileName="MetricSet" PageBreakSelector=".pdf-page-break" /> 
</telerik:RadClientExportManager>

I've tried the javascript by passing a pdfSettings to the export, and also by using set_pdfSettings. I get the same problem either way.

function onClientPdfExported(sender, args) { 
     document.getElementById("modalDivPDF").style.display = "none";
     document.body.style.cursor = 'default';
    } 

function pdfPageSection() { 
     document.getElementById("modalDivPDF").style.display = "block";
     document.body.style.cursor = 'wait';

     var pdfSettings = {
          filename: "MetricSet",
          margin: { top: 25, left: 15, bottom: 10, right: 15 },
          pageBreakSelector: ".pdf-page-break"
     }

        $ = $telerik.$; 
        var $dashboardPanel = $(".DashboardPanel"); 
        var manager = $find("<%= PDFExportManager.ClientID %>"); 
        manager.set_pdfSettings(pdfSettings);
        manager.exportPDF($dashboardPanel); //, pdfSettings); 
    } 

What am I doing wrong? Why do I get "undefined" for my filename???

Thanks,

Brent