bootstrap tour with model view

I`m using bootstrap tour to build a web tour page. Now I have a problem: 1、this is my code:

{
            element : ".tourstep4",
            title : "step 4",
            placement : "left",
            reflex : true,
            onNext : function(tour){
                $('#myModal').modal('show');

                tour.goTo(4);
            },
            content : "choose 'add page'"
        }, {
            element : ".tourstep5",
            title : "step 5",
            placement : "left",
            content : "choose 'something'"
        }

2、I want to open a model view create by bootstrap ,but when I want to go step 5,the modal is open ,but the tour is gone ,and have some problem in my Chrome console

Uncaught TypeError: this.backdrop.remove is not a function

3、while I want restart the bootstrap tour, and it does not do anything even I refresh the chrome.

briefly： how to use bootstrap tour open a modal view . and show another step in this modal view.