I have a large index, on which Highlighter.Net works fine, but FastVectorHighlighter returns null as a Best Fragment on Some documents.
the searcher works fine. It is just the highlighter. The field has been indexed in the same manner for all documents, so I fail to understand Why it highlights some documents but not all.
Using Lucene.Net 2.9.2, built from trunk rev942061
Problem solved by the nice people at lucene-net-user. I was passing the document sequence number in the Hits object, where I should have been passing the sequence number in the lucene index. Read full mailing list thread starting here