Problme of modifying generated index..

[qi wu]

Hi,
I am trying to modify the content of certain field in generated index , and the 
fields with "Field.Store.NO" like archor,content,site are lost, the source code 
is listed blow:

    IndexReader ir = IndexReader.open(indexDir);
    IndexWriter writer=new IndexWriter("C:\\nutch9Ship\\lv321DB\\index01", 
analyzer ,
    true);
    .......
    Document doc=ir.document(j);
    doc.removeField("time");
    doc.add(new 
Field("time",getDate(cont.toString()),Field.Store.YES,Field.Index.UN_TOKENIZED));
    System.out.println(doc.getFields().size());
    writer.addDocument(doc);
        .......
The filed like archor,content,site can be found through Luke for original 
index,but can't to find in the new generated index through Luke..Anyone could 
give me a hint on this? I am also looking into this 

Thanks
-Qi