Control Room metering

Hi to everyone,

I got some misunderstandings with level metering in main stereo-buss and that in Control Room. While I use FabFilter Pro L maximiser in stereo-buss insert - indicator shows 0 db (for example). At the same time indicator Loudness(and RMS) of Control Room shows clipping +6-7 db. How should I relate to this? How to understand?
Excuse me my English pls.

Win 8.1-64 bit / Cubase 8.0-64 bit / RME Fireface UCX / i-7 4770 / GA Z87X-UDH5-CF