Having trouble getting the text entered to appear when I click add task

// Problem: User interaction doesn't provide desired results
// Solution: Add interactivity, so the user can manage daily tasks.

// < -------------- Plan -------------- >

var taskInput = document.getElementById("new-task"); // new-task
var addButton = document.getElementsByTagName("button")[0]; // first button
var incompleteTasksHolder = document.getElementById("incomplete-tasks"); // #incomplete-tasks
var completedTasksHolder = document.getElementById("completed-tasks"); // #completed-tasks


// New Task List Item
var createNewTaskElement = function(taskString) {

  // Create List Item
  var listItem = document.createElement("li");

  // input (checkbox)  
  var checkBox = document.createElement("input"); // Type is checkbox

  // label
  var label = document.createElement("label");

  // input (text)
  var editInput = document.createElement("input");

  // button with a class and the text of edit
  var editButton = document.createElement("button");

  // button with a class and the text of delete
  var deleteButton = document.createElement("button");

  // Each element needs modifying   
  checkBox.type = "checkbox";
  editInput.type = "text";

  editButton.textContent = "Edit";
  editButton.className = "edit";
  deleteButton.textContent = "Delete";
  deleteButton.className = "delete";

  label.innerText = taskString;


  // Each element needs appending 
  listItem.appendChild(checkBox);
  listItem.appendChild(label);
  listItem.appendChild(editInput);
  listItem.appendChild(editButton);
  listItem.appendChild(deleteButton);

  return listItem;
}


/* When the user clicks on the add task button: it will createNewTaskElement with all of the complexity in the fuction, then return that item back into the variable listItem in the addtask function then append it to the incompleteTasksHolder */

// Add a new task
var addTask = function() {  
  console.log("Add task...");  
  // Create a new list item with the text from #new-task:  
  var listItem = createNewTaskElement(taskInput.value);  
  // Append listItem to incompleteTasksHolder
  incompleteTasksHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskCompleted); 
}

// Edit an existing task
var editTask = function() {
  console.log("Edit task...");
  /* When the Edit button is pressed: 
     If the class of the parent (li) is editMode,
     Switch from .editMode and make the label text 
     become the inputs' value
     Else
     switch to .editMode
     and the input value becomes the label's text
     Toggle .editMode on the parent (li)
  */  

}


// Delete an existing task
var deleteTask = function() {
  console.log("Delete task...");

  var listItem = this.parentNode;
  var ul = listItem.parentNode;

  // Remove the parent (li) from the unordered list  
  ul.removeChild(listItem);

} 

// Mark a task as complete
var taskCompleted  = function() {
  console.log("Task completed...");

  //Append the task (li) to the #complete-tasks id  
  var listItem = this.parentNode;
  completedTasksHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskIncomplete);

}

// Mark a task as incomplete
var taskIncomplete = function() {
  console.log("Task incomplete...");

  // Append the task (li) to the #incomplete-tasks id
  var listItem = this.parentNode;
  incompleteTasksHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskCompleted);  

}


// < -------------- Perform -------------- >

  // Function that will bind the task events and select the li

  var bindTaskEvents = function(taskListItem, checkBoxEventHandler) {
    console.log("Bind list item evevnts");

    //select taskListItem's children (child of ul = li)
    var checkBox = taskListItem.querySelector("input[type=checkbox]");
    var editButton = taskListItem.querySelector("button.edit");
    var deleteButton = taskListItem.querySelector("button.delete");

    // bind editTask to edit button
    editButton.onclick = editTask;

    // bind the deleteTask to the delete checkBox
    deleteButton.onclick = deleteTask;

    // bind the checkBoxEventHandler to the checkbox
    checkBox.onchange = checkBoxEventHandler;
  }

// Set the click handler to the addTask function
  addButton.onclick = addTask;



// cycle over the incompleteTasksHolder ul list items
for (var i = 0; i < incompleteTasksHolder.children.length; i++) {
  // bind events to list item's children (taskCompleted)
  bindTaskEvents(incompleteTasksHolder.children[i], taskCompleted);
}



// cycle over the completeTasksHolder ul list items
for (var i = 0; i < completedTasksHolder.children.length; i++) {
// bind events to list item's children (taskIncomplete)addButton
  bindTaskEvents(completedTasksHolder.children[i], taskIncomplete);
}