navmesh multiple targets

Lads,

I'm using NavMeshAgent for a little zombie hunting, however I'm having a problem setting multiple target destinations. Currently I've just edited the SampleAgentScript by adding extra targets like so:

 public class SampleAgentScript : MonoBehaviour 
 {
     public Transform target1;
     public Transform target2;
     public Transform target3;
     public Transform target4;
         NavMeshAgent agent;
 
 
         void Start ()
     {
         agent = GetComponent<NavMeshAgent> ();
     }
 
 
         void Update () 
     {
             agent.SetDestination(target1.position);
             agent.SetDestination(target2.position);
             agent.SetDestination(target3.position);
             agent.SetDestination(target4.position);
     }
 }

The result however are not predictable particularly when I add another agent... I'd assume that the navmeshagent would go to the first target, then the second, etc... but no such luck. The navmeshgagent doesn't seem to move in a predictable fashion. Any thoughts?...

Thanks,

Stef