Error 0029

I am receiving the Error 0029 on my Boolean ‘inside’, because I’m apparently converting it into a string in my code. What am I doing wrong?

Full Error:
Cannot convert type ‘string’ to 'bool

Code:
using UnityEngine;
using System.Collections;

public class triggerZone : MonoBehaviour {
	public AudioClip lockedsound;
	public Light doorlight;
	public GUIText texthint1;
	public static bool inside = true;
	// Use this for initialization
	void Start () {
	
	}
	
	// Update is called once per frame
	void Update () {
	
	}
	void OnTriggerEnter(Collider Col){	
		if (Col.gameObject.tag = "Player") {
			inside = (bool) true;
		if (inventory.charge == 4) {
			transform.FindChild ("door").SendMessage ("DoorCheck");
			if (GameObject.Find ("chargeHUDGUI")) {
				Destroy (GameObject.Find ("chargeHUDGUI"));
				doorlight.color = Color.green;
			}
		} else if(inventory.charge > 0 && inventory.charge < 4){
		//	TextHints.SendMessage("ShowHint" , "I think it needs more power!", UnityEngine.SendMessageOptions);
			
		} else {
				AudioSource.PlayClipAtPoint (lockedsound, transform.position);
				Col.gameObject.SendMessage("HUDon");
//			TextHints.SendMessage("ShowHint" , "This Door is locked, I need to power it!", UnityEngine.SendMessageOptions);
			}

		
	}

Text is of type