Unable to add points on Tone curve.

[#1]

I'm using LrC version 10.1, I don't have the option (button) to add points on the Tone Curve.

[#2]

I'm using LrC version 10.1, I don't have the option (button) to add points on the Tone Curve.

[#3 · Accepted solution]

It's the second button from the left.

Doesn't your Tone curve panel look this?