Weird error while trying to call a void from another class

Hey everyone! Ive been trying for a while now to get this working, and cant seem to find the reason why i keep getting this error. What im trying to do is make platform disappear after 2 seconds that player enters the platform childs triggered collider. It seems to call the function but returns this error:

Couldn't extract exception string from exception (another exception of class 'InvalidCastException' was thrown while processing the stack trace)...

Heres the code:

 void OnTriggerEnter(Collider c){
         if(c.transform.parent.CompareTag("Disappearing")){
             DisappearingPlatform dp = c.transform.parent.GetComponent<DisappearingPlatform> ();
             dp.StartDisappearing();
         }
     }

And the class im trying to call:

 using UnityEngine;
 using System.Collections;
 
 public class DisappearingPlatform : MonoBehaviour {
 
     public float disappearDelay = 2f;
     public float disappearTime = 5f;
     float delay;
     float cooldown;
     bool notDisappearingAlready;
 
     void Start(){
         delay = disappearDelay;
         cooldown = disappearTime;
         notDisappearingAlready = true;
     }
 
     public void StartDisappearing(){
         Disappear ();
     }
     void Disappear(){
         if(notDisappearingAlready){
             notDisappearingAlready = false;
             delay -= Time.deltaTime;
         }
         if(delay <= 0){
             transform.collider.enabled = false;
             transform.renderer.enabled = false;
             cooldown -= Time.deltaTime;
         }
         if(cooldown <= 0){
             transform.collider.enabled = true;
             transform.renderer.enabled = true;
             cooldown = disappearTime;
             delay = disappearDelay;
             notDisappearingAlready = true;
         }
     }
 
 }