To set keyframes on a specific property, it must be selected.
To select a property in the Properties window:
If the name of the property is highlighted in dark blue, the property is selected and you can animate it. Properties you can animate always have Keyframe (K) and Animate (A) buttons.
If the name of the property is highlighted in dark gray, the property is selected but you cannot animate it.
If a property is highlighted light blue before you click on it, it is already selected for animation and you do not need to click it. See Keying modes for more information.
To select a property in the Navigator window:
If the name of the property is highlighted blue, the property is selected and you can animate it. Properties you can animate always have Keyframe (K) and Animate (A) buttons.
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