DPM doesn't clear transaction logs

We use DPM 2012 to backup Exchange 2013. It works as shown the screenshot.

However, the Exchange Admin Center shows no full backup.

Also, we have a lot old transaction logs. How to DPM clear the transaction logs?

Bob Lin, MCSE & CNE Networking, Internet, Routing, VPN Networking, Internet, Routing, VPN Troubleshooting on http://www.ChicagoTech.net How to Install and Configure Windows, VMware, Virtualization and Cisco on http://www.HowToNetworking.com