SQL Server 2000 Database Maintenance

I have the database maintenance set to delete backups older than 7 days but it does not. These backups continue to grow until all disk space is used. I have read elsewhere that perhaps backup software is locking the files. My Veritas backup runs at 2AM and the SQL backup at 10PM, so I don’t think this is an issue, but I could be wrong. I am relative newb to SQL so any info you may be able to supply in regards to this problem would be greatly appreciated. If more info is needed from me, just ask.