back up failed

Just checking some past cases - looks like there might be a fix for this incorporated in v21 of the product, or maybe for those customers on v21 the registry change worked. Would recommend upgrading if possible.

Alternatively review the Microsoft Exchange options in the backup job (eg referencing the consistency check options here). Also worth confirming that the version of Exchange you are running is supported by the BE version you are on - as per the SCL:
backupexec.com/compatibility

aka

https://www.veritas.com/content/support/en_US/article.100040087 

Would recommend you try the folowing possible solution:

https://www.veritas.com/support/en_US/article.100014715 - 
Consistency check fails with error code -1030 when multiple Exchange databases are selected

As a matter of interest are the Exchange server and Backup Exec server the same box?