Load document failed

Question

Platform: Oracle9iR2, chinese version.
I created a table as "create table xmltable of xmltype;", then use the following statement to load document via jdbc driver:
//str is the content of my xml file.
XMLType xt = XMLType.createXML(conn, str);
stmt.setObject(1, xt);
stmt.executeUpdate();
But the following exception occured:
java.sql.SQLException: Non supported character set: oracle-character-set-852
     at oracle.gss.util.NLSError.throwSQLException(NLSError.java:46)
     at oracle.sql.CharacterSetUnknown.failCharsetUnknown(CharacterSetFactoryThin.java:171)
     at oracle.sql.CharacterSetUnknown.convert(CharacterSetFactoryThin.java:135)
     at oracle.xdb.XMLType.getBytesString(XMLType.java:1215)
     at oracle.xdb.XMLType.getBytesValue(XMLType.java:1151)
     at oracle.xdb.XMLType.toDatum(XMLType.java:323)
     at oracle.jdbc.driver.OraclePreparedStatement.setORAData(OraclePreparedStatement.java:2700)
     at oracle.jdbc.driver.OraclePreparedStatement.setObject(OraclePreparedStatement.java:3006)
why? Whatever the encoding charset is, it always failed. The following text are from my xml file, test.xml.
<?xml version="1.0"?>
<site>
</site>

Answer 1

The PDF file does not appear to be saved or properly scanned.  Normally, the scan ends and a preview appears in a window that can be saved.  In the case of PDF, the preview doesn't appear.  It's as if the document has not been scanned at all.  
If I try to scan a document using a JPEG setting everything works fine.   That is the preview document appears, which can then be saved. 
Very perplexing. 
D.