Dialog box is not closing flutter

Here's my Alert dialog code: I've added Navigator.pop(context); in the tapped method call. But it's not closing.

 showLoginDialog(BuildContext context,
  {TextEditingController usernameController,
  TextEditingController loginController}) {
var textController = new TextEditingController();
var nameTextController = new TextEditingController();
String dateToPost;
Alert(
    context: context,
    title: "Add Profile",
    content: Column(
      children: <Widget>[
        TextField(
          controller: nameTextController,
          decoration: InputDecoration(
            labelText: 'Name',
          ),
        ),
        TextField(
          controller: textController,
          onTap: () async {
            DateTime date = DateTime(1900);
            //FocusScope.of(context).requestFocus(new FocusNode());

            date = await showDatePicker(
                context: context,
                initialDate: DateTime.now(),
                firstDate: DateTime(1900),
                lastDate: DateTime.now());

            var formatter = new DateFormat('dd MMM yyyy');
            var formatterToPost = new DateFormat('yyyy-MM-dd');
            String formatted = formatter.format(date);
            dateToPost = formatterToPost.format(date);
            print(formatted);

            textController.text = formatted;
          },
          decoration: InputDecoration(
            labelText: 'Birth Date',
          ),
        ),
      ],
    ),
    buttons: [
      DialogButton(
        onPressed: () {
          Navigator.pop(context);
           _saveData(textController.text, nameTextController.text,
               dateToPost);
        },
        child: Text(
          "Add",
          style: TextStyle(color: Colors.white, fontSize: 20),
        ),
      )
    ]).show();

}

Also, is shows error on second time click: The method 'call' was called on null. Receiver: null Tried calling: call()

I've solved this issue using

Navigator.of(context, rootNavigator: true).pop();