SnapManager for SQL does not delete old filestream snapshots?

I have a SQL database with file stream. mdf is in a dedicated vol/lun. ldf is in a dedicated vol/lun. filestream is in a dedicated vol/lun. SMSQL backup job have settings to keep 10 snapshots on primary filer. Snapvault backup is for 6 months on secondary filer. On primary filder, old snapshots on mdf volume were deleted but old snapshots in ldf and filestream volumes are not being deleted. Is this expected or I missed some configuration on the backup job? Thanks.