Invoke fails: "Trying to Invoke method: InputController.enableInput couldn't be called."

Hey all, I've used Invoke successfully in the past, but for a reason I just can't figure out, it's failing on my enableInput function. I've searched for this exception and as far as I can tell, it has only cropped up when someone passed a misspelled method name to Invoke or tried to use it with a coroutine. I'm not familiar with coroutines, but I suppose that neither of those conditions apply in this case. Here are (what I consider to be) the relevant snippets of InputController.cs:

 public void disableInput(float timer = 0)
 {
     inputAllowed = false;

     if (timer > 0)
     {
         Invoke ("enableInput", timer);
     }
 }

 public void enableInput(float timer = 0)
 {
     inputAllowed = true;

     if (timer > 0)
     {
         Invoke ("disableInput", timer);
     }

 }

 void Update () {
 ...
     if (mouseLeftClicked == true) {
     ...
        disableInput (.2f);
     }
     ...
 }

When I run the game and click, disableInput(.2f) gets called and the program enters the disableInput method with timer > 0. When it tried to execute the Invoke line, it throws this exception:

Trying to Invoke method: InputController.enableInput couldn't be called.

What's wrong? Thank you!

P.S. Here's the full script in case more context is needed.

 using UnityEngine;
 using System.Collections;
 
 public class InputController : MonoBehaviour {
     bool inputAllowed = true;
     bool mouseLeftHeld;
     bool mouseLeftClicked;
 
     EntityController characterController;
 
     CursorController cursorController;
 
     MovementController movement;
 
     DialogueController dialogueController;
 
     RaycastHit2D cursorHit;
 
     Vector3 mouseWorldPos;
     
 
     void Start () {
         characterController = gameObject.GetComponent<EntityController>();
         cursorController = gameObject.transform.GetComponent<CursorController> ();
         movement = gameObject.GetComponent<MovementController>();
         dialogueController = gameObject.GetComponent<DialogueController>();
     }
 
     void cursorRaycast()
     {
         mouseWorldPos = Camera.main.ScreenToWorldPoint (Input.mousePosition);
         cursorHit = Physics2D.Raycast (mouseWorldPos, Vector2.zero, 0);
     }
 
     public void disableInput(float timer = 0)
     {
         print ("Disabling input with t = " + timer);
         inputAllowed = false;
 
         if (timer > 0)
         {
             Invoke ("enableInput", timer);
         }
     }
 
     public void enableInput(float timer = 0)
     {
         print ("Enabling input");
         inputAllowed = true;
 
 
         if (timer > 0)
         {
             Invoke ("disableInput", timer);
         }
 
     }
 
     void Update () {
         //print (inputAllowed);
         cursorRaycast ();
         getMouseStates ();
 
         cursorController.setCursorToDefault ();
 
         if(Input.GetKeyDown ("escape") == true)
         {
             Application.Quit ();
         }
 
         if (inputAllowed == true)
         {
             if (cursorHit.collider != null) {
                 if (cursorHit.transform.tag == "NPC") {
                     cursorController.setCursorToTalk ();
                 }
             }
 
             if (mouseLeftClicked == true) {
                 //print ("The mouse has been clicked");
 
                 movement.stopMovingTo();
                 
                 if (cursorHit.collider != null) {
                     if (cursorHit.transform.tag == "ColliderDummy") {
                         if (cursorHit.transform.parent.transform.tag == "Door") {
                             //print ("A door has been clicked");
                             DoorController doorController = cursorHit.transform.parent.gameObject.GetComponent<DoorController> ();
                             doorController.toggleDoor ();
                         }
                     } else if (cursorHit.transform.tag == "NPC") {
                         dialogueController.talkTo(cursorHit.transform.gameObject);
                     }
                     else
                     {
                         movement.moveTo (mouseWorldPos);
                     }
                 }
                 else
                 {
                     movement.moveTo (mouseWorldPos);
                 }
 
                 disableInput (.2f);
             }
             else if (mouseLeftHeld == true)
             {
                 movement.stopMovingTo();
                 movement.moveToward (mouseWorldPos);
             }
 
             if (Input.GetKeyDown ("h") == true)
             {
                 characterController.say ();
             }
         }
     }
 
 
     void getMouseStates()
     {
         mouseLeftHeld = Input.GetMouseButton (0);
         mouseLeftClicked = Input.GetMouseButtonDown (0);
     }
 
     public bool inputIsAllowed()
     {
         return inputAllowed;
     }
 }