Is the collider a trigger?

A trigger doesn't collide with rigid bodies. Instead it sends OnTriggerEnter, OnTriggerExit and OnTriggerStay message when a rigidbody enters or exits the trigger.

	// Turns the attached to collider into a trigger.
	collider.isTrigger = true;

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        collider.isTrigger = true;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		collider.isTrigger = true