NullPointerException while sorting on INT

[Bhavin Pandya]

Hi friends,

I am getting NullPointerException while sorting on a field using SortField.INT
same is working for SortField.STRING

Code Snippet:
                SortField sortfield = new 
SortField("CURRENT_BID",SortField.INT,false); // asceding sort on current bid 
value
                Sort sort = new Sort();
                sort.setSort(sortfield);
                hits = msearcher.search(bqmain,sort);  // this statement 
generates NullPointerException

Stack Trace:
java.lang.NullPointerException
        at 
org.apache.lucene.search.MultiSearcherThread.hits(ParallelMultiSearcher.java:286)
        at 
org.apache.lucene.search.ParallelMultiSearcher.search(ParallelMultiSearcher.java:141)
        at org.apache.lucene.search.Hits.getMoreDocs(Hits.java:65)
        at org.apache.lucene.search.Hits.<init>(Hits.java:52)
        at org.apache.lucene.search.Searcher.search(Searcher.java:53)
        at _auctionSearcher__jsp._jspService(_auctionSearcher__jsp.java:359)

Same is working if i change "SoftField.INT" to "SortField.STRING"....

In index the field "CURRENT_BID" has no null value in any document....

I am using lucene 2.1.

Thanks.
Bhavin pandya