Bad documents on reindexating Verity

[Massoroto]

Hi,

after reindexating verity collection OWNER it produced the error of 902
Bad Documents:

Primary Collection: maq1:OWNER
State: Finished
Scheduling: Not Set
Chaining:
Prior Job(s): MARK_job
Subsequent Job(s): AGENT_job
Run this Job: Only on success of any prior job
Documents Crawled: 191018
Documents Indexed: 191018
Documents Inserted: 192024
Documents Skipped: 0
Documents Skipped (Duplicate): 0
Documents Skipped (not Found): 0
Documents Deleted: 104
Bad Documents: 902
Elapsed Time: 2:06:08

Does anybody know why it may be produced? Its is a data or a
configuration problem? Is it possible that a purge was not made before?

Thank you all,

Massoroto