isLoggedIn（）方法不起作用，我一直在尝试这段代码，但它无助

Question

  function isLoggedIn(req,res,next){  // middleware
        if(req.isAuthenticated()){
            return next();
        }
        res.redirect("/login");
        console.log("It's not working");
    }

   app.get("/campgrounds/:id/comments/new", isLoggedIn ,function(req,res){
   Campground.findById(req.params.id, function(err, campground){
   if(err){
       console.log(err);
   }else{
        res.render("comments/new.ejs",{campground:campground});
        console.log("It's working")
   }
   }); 
});


    app.post("/campgrounds/:id/comments", isLoggedIn , function(req,res){
   Campground.findById(req.params.id, function(err,campground){
        if(err){
        console.log(err);
        res.redirect("/campgrounds");
    }else{
        Comment.create(req.body.comment, function(err,comment){
            if(err){
                console.log(err);
            }else{
                campground.comments.push(comment);
                campground.save();
                res.redirect("/campgrounds/" + campground._id);
            }
        });
    }
  });
});

每当我尝试在用户登录时添加评论时，它会向我显示错误“它无法正常工作”，如此处的console.log。请帮忙