NoClassDefFoundError

I found this Exception in the std output, I'm I missing any Lucene jar files ?

java.lang.NoClassDefFoundError: org/apache/lucene/util/BitVector
at org.apache.lucene.index.SegmentReader.initialize(SegmentReader.java:116)
at org.apache.lucene.index.SegmentReader.<init>(SegmentReader.java:94)
at org.apache.lucene.index.IndexWriter.mergeSegments(IndexWriter.java:480)
at org.apache.lucene.index.IndexWriter.optimize(IndexWriter.java:366)
at bucket.search.lucene.LuceneTaskQueue.processWritingTasks(LuceneTaskQueue.java:189)
at bucket.search.lucene.LuceneTaskQueue.flush(LuceneTaskQueue.java:148)
at com.atlassian.confluence.search.lucene.IndexQueueFlusher.execute(IndexQueueFlusher.java:39)
at org.quartz.core.JobRunShell.run(JobRunShell.java:191)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:516)