HDCP error when playing HD movie in iTunes through Thunderbolt dock
I connected my MacBook Air 2011 to a Belkin Thunderbolt 2 Express Dock HD. The dock is then connected with an HDMI cable to LG 27MT57D as a independent display. When I try to play an HD movie from iTunes which I purchased some time ago, I got the HDCP error message.
However, both the MacBook Air, Belkin dock and the LG monitor are capable of HDCP. I wonder if this is a issue of the Thunderbolt port of MacBook Air 2011?
Is there any board members having the same issue as me?
MacBook Air, OS X El Capitan (10.11.4)