XML request converted to lowercase

Hi all,
I'm trying to provide support to a user of contribution code I wrote for 
osCommerce to track UPS packages.  Below is a snip of the XML request:
$accessRequestHeader =
            "<?xml version=\"1.0\"?>\n".
            "<AccessRequest xml:lang=\"en-US\">\n".
            "   <AccessLicenseNumber>". $access_key ."</AccessLicenseNumber>\n".
            "   <UserId>". $userid ."</UserId>\n".
            "   <Password>". $pass ."</Password>\n".
            "</AccessRequest>\n";
        $trackingServiceSelectionRequestHeader =
            "<?xml version=\"1.0\"?>\n".
            "<TrackRequest xml:lang=\"en-US\">\n".
            "  <Request>\n".
            "    <TransactionReference>\n".
            "      <CustomerContext>UPS Package Tracking</CustomerContext>\n".
            "      <XpciVersion>1.0001</XpciVersion>\n".
            "    </TransactionReference>\n".
            "    <RequestAction>Track</RequestAction>\n".
            "    <RequestOption>" . $activity . "</RequestOption>\n".
            "  </Request>\n".
            "  <TrackingNumber>" . $tracknum . "</TrackingNumber>\n" .
            "</TrackRequest>\n";

$xmlRequest = $accessRequestHeader . $trackingServiceSelectionRequestHeader;

If he echo's $xmlRequest it shows up in the browser source as all 
lowercase.  This results in the script failing because it checks the 
XpciVersion to make sure it is 1.0001.  This behavior is not the same on my 
server (mine shows properly-cased XML).
Any thoughts?  TIA

Steve