Older backup dissappear when creating new one

[HerbertK]

Can anybody give me a clue about an issue I have regarding  a dissappearing backup when I create a new one?

I have a large NAS with 3 partitions which can be accessed as separate network drives by Backup Exec 2012.

I have created a backup job consisting out of 3 stages that have 3 starting dates each one week after each other and will be repeated each 21 days. Each stage stores the data to a different drive letter. After three weeks the first drive should be overwritten by a new backup.

The "Keep for" period of each stage is set to 20 days.

Currently when a new backup is created (nicely to the next drive as intented) the one made the week before is removed. Why?

[Siddhant_Saini]

Hello,
Based on the situation, I am 'speculating' that DLM is marking those files for deletion(considering that you have three stages running full backups of the same server to different storage devices). To check it, please click on the Backup Exec icon(on the top left) > Configuration and Settings > Audit Log. Under 'Select Category to view' select 'Backup Set retention' and check if any of your backup sets are marked for being overwritten(I would need the details mentioned below the 'Message' area). 

[HerbertK · Accepted solution]

This issue can be closed, I still don't know how (didn't change settings) but now it works as expected.