Error "Input Axis Vertical is not set up"

I’m taking a tutorial for an Enemy Kills Player Tutorial. I’ve looked through my script multiple times and this is the only error that shows up. It lets me play the game, but the controller itself won’t work. Why is this?

The error suggests that “Vertical” is not an axis set up in your input manager settings. Double check your input manager settings for this axis, and make sure your string does not contain leading or trailing spaces as this will cause it to fail to find the input axis as well.

problem fixed here : Input Axis vertical is not setup unity | Input Axis horizontal is not setup unity - YouTube