OnCollisionEnter doesn't trigger - unity3d

Question

using UnityEngine;
using System.Collections;
public class changedirection : MonoBehaviour {
void OnCollisionEnter(Collision col)
{
if (col.gameObject.name == "soldier")
{
GameObject go = col.gameObject;
Move move = go.GetComponent<Move>();
move.direction = -1;
}
}
}
Both objects that collide are triggers, sorry didn't program with unity for over a year

Answer 1

Static colliders don't collide with each other.
There was a table that showed when collision and trigger events are fired on docs.unity3d.com. But they have updated the site and now I can't find it. I still have it local. So, here it is.
Collision action matrix
Depending on the configurations of the two colliding Objects, a number of different actions can occur. The chart below outlines what you can expect from two colliding Objects, based on the components that are attached to them. Some of the combinations only cause one of the two Objects to be affected by the collision, so keep the standard rule in mind - physics will not be applied to objects that do not have Rigidbodies attached.
Collision detection occurs and messages are sent upon collision
╔═══════════╦══════════╤═══════════╤═══════════╤══════════╤═══════════╤═══════════╗
║ ║ Static │ Rigidbody │ Kinematic │ Static │ Rigidbody │ Kinematic ║
║ ║ Collider │ Collider │ Rigidbody │ Trigger │ Trigger │ Rigidbody ║
║ ║ │ │ Collider │ Collider │ Collider │ Trigger ║
║ ║ │ │ │ │ │ Collider ║
╠═══════════╬══════════╪═══════════╪═══════════╪══════════╪═══════════╪═══════════╣
║ Static ║ │ Y │ │ │ │ ║
║ Collider ║ │ │ │ │ │ ║
╟───────────╫──────────┼───────────┼───────────┼──────────┼───────────┼───────────╢
║ Rigidbody ║ Y │ Y │ Y │ │ │ ║
║ Collider ║ │ │ │ │ │ ║
╟───────────╫──────────┼───────────┼───────────┼──────────┼───────────┼───────────╢
║ Kinematic ║ │ Y │ │ │ │ ║
║ Rigidbody ║ │ │ │ │ │ ║
║ Collider ║ │ │ │ │ │ ║
╟───────────╫──────────┼───────────┼───────────┼──────────┼───────────┼───────────╢
║ Static ║ │ │ │ │ │ ║
║ Trigger ║ │ │ │ │ │ ║
║ Collider ║ │ │ │ │ │ ║
╟───────────╫──────────┼───────────┼───────────┼──────────┼───────────┼───────────╢
║ Rigidbody ║ │ │ │ │ │ ║
║ Trigger ║ │ │ │ │ │ ║
║ Collider ║ │ │ │ │ │ ║
╟───────────╫──────────┼───────────┼───────────┼──────────┼───────────┼───────────╢
║ Kinematic ║ │ │ │ │ │ ║
║ Rigidbody ║ │ │ │ │ │ ║
║ Trigger ║ │ │ │ │ │ ║
║ Collider ║ │ │ │ │ │ ║
╚═══════════╩══════════╧═══════════╧═══════════╧══════════╧═══════════╧═══════════╝
Trigger messages are sent upon collision
╔═══════════╦══════════╤═══════════╤═══════════╤══════════╤═══════════╤═══════════╗
║ ║ Static │ Rigidbody │ Kinematic │ Static │ Rigidbody │ Kinematic ║
║ ║ Collider │ Collider │ Rigidbody │ Trigger │ Trigger │ Rigidbody ║
║ ║ │ │ Collider │ Collider │ Collider │ Trigger ║
║ ║ │ │ │ │ │ Collider ║
╠═══════════╬══════════╪═══════════╪═══════════╪══════════╪═══════════╪═══════════╣
║ Static ║ │ │ │ │ Y │ Y ║
║ Collider ║ │ │ │ │ │ ║
╟───────────╫──────────┼───────────┼───────────┼──────────┼───────────┼───────────╢
║ Rigidbody ║ │ │ │ Y │ Y │ Y ║
║ Collider ║ │ │ │ │ │ ║
╟───────────╫──────────┼───────────┼───────────┼──────────┼───────────┼───────────╢
║ Kinematic ║ │ │ │ │ │ ║
║ Rigidbody ║ │ │ │ Y │ Y │ Y ║
║ Collider ║ │ │ │ │ │ ║
╟───────────╫──────────┼───────────┼───────────┼──────────┼───────────┼───────────╢
║ Static ║ │ │ │ │ │ ║
║ Trigger ║ │ Y │ Y │ │ Y │ Y ║
║ Collider ║ │ │ │ │ │ ║
╟───────────╫──────────┼───────────┼───────────┼──────────┼───────────┼───────────╢
║ Rigidbody ║ │ │ │ │ │ ║
║ Trigger ║ Y │ Y │ Y │ Y │ Y │ Y ║
║ Collider ║ │ │ │ │ │ ║
╟───────────╫──────────┼───────────┼───────────┼──────────┼───────────┼───────────╢
║ Kinematic ║ │ │ │ │ │ ║
║ Rigidbody ║ Y │ Y │ Y │ Y │ Y │ Y ║
║ Trigger ║ │ │ │ │ │ ║
║ Collider ║ │ │ │ │ │ ║
╚═══════════╩══════════╧═══════════╧═══════════╧══════════╧═══════════╧═══════════╝
Layer-Based Collision Detection
In Unity 3.x we introduce something called Layer-Based Collision Detection, and you can now selectively tell Unity GameObjects to collide with specific layers they are attached to. For more information click here.