Ink - Displaying Messages with Time intervals

Hi there. I am working on text-based game and using Ink plugin. Basically i want to display the text lines and responses/answers of the story, with time intervals like in every 5 sec, like in the game LIFELINE or ZARYA. I have tried to use Invoke method but it stops the Unity so i guess there is an error on function that i use in the method. Here the code that i am trying to run;

Code (CSharp):

1.  
2. using Ink.Runtime;
3. using UnityEngine.UI;
4.  
5. void Awake ()
6.     {
7.         _inkStory = new Story (inkAsset.text);
8.         storyNeeded = true;
9.                  Invoke("Spawn", 5f);
10.     }
11.  
12. void Update()
13. {
14.  while (_inkStory.canContinue)
15.             {
16.  if (_inkStory.currentChoices.Count > 0)
17.            {
18.                 //President variable
19.                 int president = (int)_inkStory.variablesState["PRESIDENT"];
20.  
21.                 RemoveButtons();
22.                 for (int ii = 0; ii < _inkStory.currentChoices.Count; ++ii)
23.                {
24.                    UnityEngine.UI.Button choice = Instantiate (button) as UnityEngine.UI.Button;
25.                    choice.transform.SetParent (_choices.transform, false);
26.                    choice.transform.Translate (new Vector2 (0, 0));
27.  
28.                    UnityEngine.UI.Text choiceText = choice.GetComponentInChildren<UnityEngine.UI.Text> ();
29.                    choiceText.text = _inkStory.currentChoices [ii].text;
30.  
31.                    UnityEngine.UI.HorizontalLayoutGroup layoutGroup = choice.GetComponent <UnityEngine.UI.HorizontalLayoutGroup> ();
32.  
33.                    int choiceId = ii;
34.                    choice.onClick.AddListener(delegate{ChoiceSelected(choiceId);});
35. }
36.            {
37.  
38.  
39. void Spawn()
40.     {
41.         GameObject message = Instantiate(_line) as GameObject;
42.         message.transform.SetParent(_content.transform);
43.         Text storyText = _line.GetComponentInChildren<Text>();
44.         storyText.transform.localPosition = new Vector2(422, -117);
45.         storyText.text = _inkStory.Continue();
46.     }

"_line" is the prefab that i instantiate with every line of the story with some icon images as messages. And i wrap the text line to the text child of the prefab. That's the way i choosed to display every messages.

Thanks for your interest.