GoogleConnect.Fetch throws Cannot pass object error

I am integrating google API into my project. I use the following code for this:

public void google()
    {

        GoogleConnect.ClientId = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
        GoogleConnect.ClientSecret = "xxxxxxxxxxxxxxxxxxxxxxxxxxxx";
        GoogleConnect.RedirectUri = Request.Url.AbsoluteUri.Split('?')[0];

        if (!string.IsNullOrEmpty(Request.QueryString["code"]))
        {
            string code = Request.QueryString["code"].ToString();
            string json = GoogleConnect.Fetch("me", code.ToString());
            GoogleProfile profile = new JavaScriptSerializer().Deserialize<GoogleProfile>(json);
            //code for showing data on my page
        }
        if (Request.QueryString["error"] == "access_denied")
        {
            ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", "alert('Access denied.')", true);
        }

    }
    public class GoogleProfile
    {
        public string Id { get; set; }
        public string DisplayName { get; set; }
        public Image Image { get; set; }
        public List<Email> Emails { get; set; }
        public string Gender { get; set; }
        public string ObjectType { get; set; }
    }

    public class Email
    {
        public string Value { get; set; }
        public string Type { get; set; }
    }

    public class Image
    {
        public string Url { get; set; }
    }

      

        
        
        
      

    

It runs when I click on google button and shows data in the first instance, but the second time I tried the following error.

Server error in application "/". Can't use object of type 'System.String' for input '? 1?'.

I also have a facebook and twitter button on the same screen, but I doubt this is causing the problem. Any suggestions would be helpful.