Logshipping trn files are not deleting


We configured logshipping for some databases. Everything is working fine. backup,copy and restore jobs are working fine, But trn files are not deleting automatically. Till last week it worked fine. but unexpectedly from 1 week the delete files automatically not happening.
I checked the permission on the network folder. everything looks fine. the sq server agent account having ful control. But why not deleting the old files?

Please suggest me what needs to check? i am not having nay clue.
backup,copy,restoration doing properly. but not deleting the backup,copy files.


What are you using for deletion?

I didnt get you.. i am not using anything for deletion.
When i configured log shipping, In the log backup settings after giving network path to backup folder then i configured such a way that delete files older than 3 days.