Can't open any xml file

I have installed apache 2.2.3 and PHP 5.1.5 on Win XP (IIS is also set up on different port) I have try the sample code from php.net; however, it keeps giving me error on opening the file please help.

<?php
$file = "data.xml";
$depth = array();
 
function startElement($parser, $name, $attrs)
{
global $depth;
for ($i = 0; $i [ $depth[$parser]; $i++) {
echo " ";
}
echo "$name\n";
$depth[$parser]++;
}
 
function endElement($parser, $name)
{
global $depth;
$depth[$parser]--;
}
 
$xml_parser = xml_parser_create();
xml_set_element_handler($xml_parser, "startElement", "endElement");
if (!($fp = fopen($file, "r"))) {
die("could not open XML input"); //it keeps dying here~~
}
 
while ($data = fread($fp, 4096)) {
if (!xml_parse($xml_parser, $data, feof($fp))) {
die(sprintf("XML error: %s at line %d",
xml_error_string(xml_get_error_code($xml_parser)),
xml_get_current_line_number($xml_parser)));
}
}
xml_parser_free($xml_parser);
?>

Thank you in advance,
Pillow