This warning occurs during point-in-time restore of archived logged Domino databases. When Domino transaction logs are replayed on Domino database for point-in-time recovery, re-generation of all NLO files referenced by that database may not be possible. Normally,Domino server provides the missing NLO files for the databases and Backup Exec reports them. In case Domino server fails to do so, this warning is issued informing that there may be some NLOfiles which are referenced by reported databases but could not be re-generated.

This is a rare situation as it happens only when performing the restore because a particular database and NLO files referenced by it have both been lost. In a normal situation, 
NLO files referenced by a deleted database are present in the Domino DAOS internal repository for a sufficient duration of time if the default prune period recommended by 
Domino is set.  Thus, Domino recovery may not be needed for re-generation of NLO files.