Advanced Retention Policy for SQL Server Backups

We are in the process of setting up our SQL Server backups to Avamar.  I do log and differential backups during the week and a weekly full for each database.  I don't do a separate monthly full or end-of-year full.  On some instances, I need to retain backups for a year and the balance I need to retain backups for 6 years for regulatory purposes.  The initial Advanced Retention we had set-up was this:

One (1) year:  14 days of daily, 4 weeks of weekly, 11 months of monthly, 365 days of yearly

Six (6) year:  14 days of daily, 4 weeks of weekly, 11 months of monthly, 6 years of yearly.

I received this warning:

The advanced retention policy option is being used by the specified Retention Policy but the schedule specified may not field the backups necessary to accommodate the retention settings.  Please review the Administrator Manual to ensure correct use of Advanced Retention Policy.

I contacted Support, and I was told I should only set the Basic Expiration Date to 1 or 6 years and not used the Advanced Retention Policy since the yearly took precedence.

Can someone give me a clear explanation on why I was receiving this warning?  Is there a reason why we can't use the Advanced Retention Policy for database backups?

Thank you!