I have a php file with an xml header and xml code, named test.php.

How do I load this file as an xml?

The following doesn't work:

$xml = simplexml_load_file('test.php');
echo $xml;

I just get a white page.

The test file is saved as php, as it's dynamic. It's loading data from the tradedoubler api. The xml looks something like this:

<voucherList>
  <voucher>
    <id>115</id>
    <programId>111</programId>
    <programName>Program 111</programName>
    <code>AF30C5</code>
    <updateDate>1332422674941</updateDate>
    <startDate>1332370800000</startDate>
    <endDate>1363906800000</endDate>
    <title>Voucher number one</title>
    <shortDescription>Short description of the voucher.</shortDescription>
    <description>This is a long version of the voucher description.</description>
    <voucherTypeId>1</voucherTypeId>
    <defaultTrackUri>http://clk.tradedoubler.com/click?a(222)p(111)ttid(13)</defaultTrackUri>
    <siteSpecific>True</siteSpecific>
  </voucher>
  <voucher>
    <id>116</id>
    <programId>111</programId>
    <programName>Program 111</programName>
    <code>F90Z4F</code>
    <updateDate>1332423212631</updateDate>
    <startDate>1332370800000</startDate>
    <endDate>1363906800000</endDate>
    <title>The second voucher</title>
    <shortDescription>Short description of the voucher.</shortDescription>
    <description>This is a long version of the voucher description.</description>
    <voucherTypeId>1</voucherTypeId>
    <defaultTrackUri>http://clk.tradedoubler.com/click?a(222)p(111)ttid(13)url(http://www.example.com/product?id=123)</defaultTrackUri>
    <siteSpecific>False</siteSpecific>
    <landingUrl>http://www.example.com/product?id=123</landingUrl>
  </voucher>
</voucherList>