Command Bar Menu - Appointment Activity -Disappearing CRM

I am facing an issue in CRM, the bug is when I create an appointment and try to save it, the commandBar go invisible after the load of the created record of the appointment. I try to inspect the javascript associated code but there is no hint about the source of the problem, I should say that after refreshing the page of the created page the command bar become visible.

OnSave: function (e) {

    EOZ.Appointment.SetPivotalId();

    var eventArgs = e.getEventArgs();

    if (Xrm.Page.ui.getFormType() == 1 && eventArgs.getSaveMode() == 1 && !saveAndClose) {
        Xrm.Page.getAttribute("createdon").addOnChange(EOZ.Appointment.CreatedOnChanged);
    }

    else {
        saveAndClose = true;
        Xrm.Page.getAttribute("createdon").removeOnChange(EOZ.Appointment.CreatedOnChanged);
    }
},

CreatedOnChanged : function () {
    var id = Xrm.Page.data.entity.getId();
    setTimeout(function () {
        Xrm.Utility.openEntityForm("appointment", id);
    }, 500);

}

NB : After a lot of javascript debugging, i noticed that the problem is only happened when the method "CreatedOnChanged" is called more than once, in the other hand if it's called just once the command bar is visible. I don't know if it's the source of the bug, but it is the only difference in the code's behaviour.