Play animation backwards

Well, I didn’t find anything to help with this thing. I have a main menu, a 3D one, and I have an “About” button, when i click that the animation plays without any problems, the problem is when I click on the “BACK” button I want the same animation to go backwards, but it doesn’t work.
I tried the animation[“name”].speed = -1; and it didn’t work, and this was the only thig I could find… If you can help me, thanks!

Set length to end:

animation["name"].speed = -1;
animation["name"].time = animation["name"].length;

or turn loop on:

animation["name"].wrapMode = WrapMode.Loop;