Unknown Identifier error: 'AstarPath'

Beginner Questions
1

From the documentation i am trying to access graph data (http://www.arongranberg.com/astar/docs/calling-pathfinding.php#), however for AstarPath.active i get and Unknown Identifier error: ‘AstarPath’. using Pathfinding; does not throw any errors.
Do i have to get any other namespaces?

2

Hi

`
using Pathfinding;

public void Start () {
AstarPath astar = AstarPath.active;
}`

The above code should work.