The most likely causes are:
 
  • The database could be in the wrong recovery mode; or
  • The database has never had a full backup before; or
  • The backups are misconfigured.
 
Recovery mode: Only databases in full or bulk logged mode allow log backups.  Check that your database is in either full or bulk logged mode.  For more information on SQL Server recovery models, see https://msdn.microsoft.com/en-us/library/ms189275.aspx

Full backups: In SQL Server, a database must have had a full backup before a log backup can be taken. So Minion Backup prevents this: if you try to take a log backup, and the database doesn't have a restore base, then the system will remove the log backup from the list. It will not attempt to take a log backup until there's a full backup in place.  Though it may seem logical to perform a full backup instead of a full, we do not do this, because log backups can be taken very frequently; we don't want to make what is usually a quick operation into a very long operation.

Other: If neither of these is the issue try the following:
 
  • Check the Minion.BackupLog and Minion.BackupLogDetails to see if log backups are being attempted and failing, for this database.
  • Check Minion.BackupSettings to be sure that either (a) the database in question has rows defined to cover all backup types, or (b) the database has NO database-specific rows defined, and therefore will use the MinionDefault settings.
  • Check Minion.BackupSettingsPath to be sure that (a) the database in question has rows defined to cover all backup types, or (b) the database has NO database-specific rows defined, and therefore will use the MinionDefault settings.
 
And as always, get support from us at www.MinionWare.net if you need it.