What's wrong with this script?

I have this script, attached to a “platform”
When the player touches it, he must get an upward force, But whe the player goes into the trigger, nothing happens. Why?

var theplayer : Rigidbody;

function OnTriggerEnter (other : Collider) {
	theplayer.AddForce(0, 100, 0);

}

Do you get any errors in the console?
Check if the code actually executes by adding a Debug.Log(“Adding force to player”); just before you add force.

If you get no errors and you get your message in the console, maybe your player is kinematic? (In such case forces won’t affect it at all)

Is the collider set to “Is Trigger”?

try to use ForceMode.VelocityChange or ForceMode.Impulse.

theplayer.AddForce(0, 10, 0, ForceMode.VelocityChange);

Character Controller overrides physics behaviour. You can’t AddForce to it. You have to use a plain old Rigidbody if you want to add forces.