Why can't I select an actor in Matinee?

I’m a complete newbie to Unreal Engine, and am experimenting with matinees. I have successfully created a camera-based matinee to play as an opening cinematic; the problem I have arises when I attempt to select an actor and then add a keyframe. For some reason, the actor and the matinee track cannot be selected simultaneously, even in different windows. In every tutorial I have seen, the tutor is able to select the door, then click on the track - the door still selected - and add a keyframe. Can anyone offer advice as to why I cannot perform this simple action?

Wow, I am an idiot. Sorry. In case anyone has a similar problem, try creating a new empty group with the object selected.