File does not begin with '%PDF-' when including image using FPDF in Classic ASP
this.Image('bg_logo_small.jpg',10,8,213,46);

./rpt/report.asp
./rpt/fpdf.asp
./rpt/bg_logo_small.jpg

./rpt/fpdf/ - this directory contains all the files extracted from fpdf1.01.zip
./rpt/fpdf/extends/
./rpt/fpdf/fonts/
./rpt/fpdf/includes/
./rpt/fpdf/models/

<%@LANGUAGE="javascript" CODEPAGE="65001"%>
<!--#include file="fpdf.asp" -->
<%
var pdf=new FPDF();

pdf.Header=function Header()
{
    this.Image('bg_logo_small.jpg',10,8,213,46);
    this.SetFont('Arial','B',15);
    this.Cell(80);
    this.Cell(30,10,'Title',1,0,'C');
    this.Ln(20);
}

pdf.Footer=function Footer()
{
    this.SetY(-15);
    this.SetFont('Arial','I',8);
    this.Cell(0,10,'Page '+ this.PageNo()+ '/{nb}',0,0,'C');
}

pdf.CreatePDF();
pdf.SetPath("fpdf/");
pdf.SetFont("Arial","",16);
pdf.Open();
pdf.AddPage();
pdf.Cell(40,10,"Hello Word!");
pdf.Close();
pdf.Output();
%>

pdf.LoadModels("bgimg")

./rpt/fpdf/models/

try with <%@LANGUAGE="javascript" %>

insted of <%@LANGUAGE="javascript" CODEPAGE="65001"%>

Just need to remove CODEPAGE="65001"