The Backup Exec Agent For Microsoft Exchange was not used to create the last Full Backeup of this database

how to fix this problem in symantec Bexec 2015
I have a Exchange 2013 on windows server 2008 r2 but when I backup incremental of exchenge the backup failed and show me this error:
The job Failed with the following error: "The Backup Exec Agent For Microsoft Exchange was not used to create the last Full Backeup of this database.You must use the Exchange Agent to run a full backup before you run a differential or incremental backup."

for more information,see v-79-57344-862 on the symantec knowledge Base.