AppSync fails for Exchange

hi all   ,

i am new to AppSync  and doing backup for Exchange Server DAG and facing the below error " No Exchange Database were founded in the state suitable for protection "

" No DAG member server registered with appSync has healthy passive copy of the database Mailbox Database01 "

before the backup was working and suddenly stopped .

expiring the copies under the Service Planes could solve the issue ? and for this expiring what it is mean and what is the effect if it is done ? and i want to make sure it will not effect the Exchange Server Database !

appreciate the support people