When Add Keys is active, you can click anywhere on a function curve (Curve Editor) or in an animation track (Dope Sheet) to insert a key at that location. Add Keys stays active until you activate a different tool.
If you add a key in a component of a multi-part controller, vertices are inserted to each curve at the time location where you clicked. For example, adding a key to the red X curve of a TCB Position track simultaneously inserts keys in the green Y curve and the blue Z curve.
The value of each added key is set by one of the following conditions:
To add keys to a function curve:
If the highlighted curve is part of a multicurve controller, vertices are inserted into each curve at the time location where you clicked. For example, if you are using a Bezier Position controller, adding a key to the red X curve of a Position track simultaneously inserts keys into the green Y and blue Z curves. This is depicted in the following illustration:
To add keys in Dope Sheet mode:
The horizontal position where you click sets the time of the key as measured on the time ruler.
The value of the new key is set by one of the following conditions:
If you are unable to add a key to a track, make sure its controller uses keys. Some controllers, such as Noise, do not.