pEmitter-Cover over life control

Hi
I follow a tutorial about particles. On one operaton in the pEmitter Style Tab in the Color over life Controls, in the tutorial the Color over life control bar is a halfton bar. I don' succeed to get the halfton bar. What do I have to modify in the preference to get the halfton bar instead of the solide black bar.
See picture
Thanks
Claude

As you can see: the halftone bar has two little triangles. Your black bar only has one.
The triangles indicate where a new color will be placed. To get a gradient like that you need to click inside the black bar to add a triangle and then with that triangle selected, you change it to the desired color.

Thank you for your reply. I can have those two arrow but it doen't change anything. With the matcontrol I think you have to do it right the firsttime because if you want to change anything it seem not to take care. Sömetime I have my text sometime not. And I can do what ever I want, I have to take the all lot out , exit from fusion and start again. I probably misst something and we will see if I find it out.
Anyway thanks. No worries I come back later for sure.
Take care of your lungs.
Claude