xmlparser failed to use URL as input

 Hello,
I have the following proc. It works fine over Oracle 10. But it gives me errors sometimes for Oracle 9.2.

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set scan off;
declare

parser DBMS_XMLPARSER.parser;
doc dbms_xmldom.DOMDocument;

begin

 -- Create a parser.
  parser := dbms_xmlparser.newParser;

  -- Parse the document and create a new DOM document.
  dbms_xmlparser.parse(parser, 'http://www.canpar.com/XML/MultiTrackingXML.jsp?language=en&barcode_nums=D002285092907');
  doc := dbms_xmlparser.getDocument(parser);

end;

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The error message is as follows:

ERROR at line 1:
ORA-29283: invalid file operation
ORA-06512: at "SYS.UTL_FILE", line 449
ORA-29283: invalid file operation
ORA-06512: at "XDB.DBMS_XSLPROCESSOR", line 15