Register.cs(31,17): error CS0029: Cannot implicitly convert type `string' to `bool'

wellp :D dont get it...

 using UnityEngine;
 using System.Collections;
 public class Register : MonoBehaviour {
 
     // This script sends informatiopn to create a game file on the server, then promts the plsyer to 
     // procede to paying for their subscription to pay for their account for that month.
 
 
     public string RegisterLink = "http://www.mysite/register.php";
 
     public string Username = "";
     public string password = "";
     public string Email = "";
     public GameObject Complete;
 
 //-----------------------------------------------------------------------------------
     public void register (){
         StartCoroutine(RegisterNewPilot());
     }
         
 //-----------------------------------------------------------------------------------
     private  IEnumerator RegisterNewPilot(){
         WWWForm form = new WWWForm();
         form.AddField("Username", Username);
         form.AddField("Email", Email);
         form.AddField("Password", password);
 
         WWW w = new WWW(RegisterLink, form);
         yield return w;
 
         if(w.error){Debug.Log("error please try again");
         } else{
             Complete.SetActive(true);
         }
         }
 
 
 
 } // end class.