When installing Data Protection Manager DPM 2012 R2 a common installation error system admins encounter is ID: 812. This is caused by the SQL Server Reporting Services misreading the reporting database. The good news is that there is an easy fix.
Open SQL Reporting Services Configuration Manager
Go to the Database tab, select change database
Select Create a new report server database and click next
Choose your SQL instance and select Test Connection, then next
Change the Database Name to your choice, select next
Select close, you are finished
Attempt to reinstall DPM and it will work!
Hope this helps!