xlsstream上PHP 4.32奇怪的输出

我一直在试图导出这个库中包含的示例excel相同的数据：

链接到图书馆

我已经得到这样一个奇怪的输出：

OUTPUT

为什么，哦，为什么….这是我的代码：

<?php include_once("header.auth.php"); require_once "xlsstream/excel.php"; $fecha_de_corrido=date("YmdHi"); $export_file = "xlsfile://tmp/InformeCertificados_".$fecha_de_corrido.".xls"; $fp = fopen($export_file, "wb"); if (!is_resource($fp)) { die("Cannot open $export_file"); } $assoc = array( array("Sales Person" => "Sam Jackson", "Q1" => "$3255", "Q2" => "$3167", "Q3" => 3245, "Q4" => 3943), array("Sales Person" => "Jim Brown", "Q1" => "$2580", "Q2" => "$2677", "Q3" => 3225, "Q4" => 3410), array("Sales Person" => "John Hancock", "Q1" => "$9367", "Q2" => "$9875", "Q3" => 9544, "Q4" => 10255), ); fwrite($fp,serialize($assoc)); fclose($fp); header ("Content-type: application/x-msexcel"); header ("Content-Disposition: attachment; filename=\"" . basename($export_file) . "\"" ); header ("Content-Description: PHP/INTERBASE Generated Data" ); readfile($export_file); exit; ?> 

Plz任何帮助将是伟大的。