on_Tween_tween_completed not triggering

I’m using this script to print out my text in a textbox one character at a time, and to do this I’m using a Tween. I have this set up so that when the Tween sends the tween_completed signal, then the variable finished becomes true. But for whatever reason, the tween_completed signal never gets sent. Does anyone see a reason that the signal wouldn’t be sent? Thank you!

extends Control

var tempdialog = (
    'Super Animal Racing is shaping up to be a great game!',
    'Thomas is so good at programming omg!',
    'Isn't this so exciting?'

var dialog_index = 0
var finished = false
var totalcharacters = 0

func _ready():

func _process(delta):
    $AnimatedSprite.visible = finished
    print("visible", finished)
    if Input.is_action_just_pressed("jump"):

func load_dialog():
    if dialog_index < tempdialog.size():
        finished = false
        $RichTextLabel.bbcode_text = tempdialog(dialog_index)
        $RichTextLabel.percent_visible = 0
            $RichTextLabel, "percent_visible", 0, 1, 1, 
            Tween.TRANS_LINEAR, Tween.EASE_IN_OUT
    dialog_index += 1

func _on_Tween_tween_completed(object, key):
    finished = true