asp.net – Facebook API – 签名请求无效. (签名无效.)

我尝试在 http://landlordscores.co.uk/account/login.aspx使用Facebook身份验证,但在登录Facebook后,回调页面显示“无效的签名请求.(无效签名.)”.应用程序ID和密码是正确的,似乎没有记录其他信息.每次我尝试使用Facebook登录时都会发生这种情况.

编辑：
为了打电话,我使用了几乎所有的代码作为样本.
在标记中：

<iframe src="<%= this.RegistrationUrl %>"
                        scrolling="auto"
                        frameborder="no"
                        style="border:none"
                        allowTransparency="true"
                        width="100%"
                        height="500">
                  </iframe>

在代码隐藏中：

public string RegistrationUrl {
    get
        {
    var url = string.Format(
    "http://www.facebook.com/plugins/registration.php?client_id={0}&redirect_uri={1}&fields={2}",FacebookApplication.Current.AppId,HttpUtility.UrlEncode(AppBLL.GetAbsoluteURL("~/Account/fbregcallback.aspx")),HttpUtility.UrlEncode("[{"name":"name"},{"name":"email"},{"name":"location"},{"name":"password","view":"not_prefilled"},{"name":"captcha"}]"));            this.RegisterUser.ContinueDestinationPageUrl = this.Request.QueryString["ReturnUrl"];
    this.hdnPassLength.Value = Membership.MinRequiredPasswordLength.ToString();
                            HttpUtility.UrlEncode("[{"name":"name"},{"name":"captcha"}]"));       
    this.hdnPassLength.Value = Membership.MinRequiredPasswordLength.ToString();
    }
}

<facebookSettings appId="xxxxxxxx"  appSecret="xxxxxxx"  cookieSupport="true" />