Blend take deactivated

Not at computer to test, but I would suggest expanding the Chloe timeline (its collapsed at the moment) then select one track at a time. Does it become active then? (I suspect it will.) I suspect you can select multiple takes, but not all types of takes support blending - e.g. I don't think you can "blend" audio. Blending is for recorded animation clips, so you can transition between the two movements more smoothly.

I normally blend by selecting a clip in the timeline then dragging the little square in the top right or left corner of that take. If no square, then that take probably does not support blending.