Express.js request params undefined

I've got the following node/express code:

app.get("/notes/:categoryName", function (res, req) {
    var categoryName = req.params.categoryName;
    res.render("notes", {title: categoryName});
});

But when I look at req.params, it's undefined.

Yet, in another controller it works fine:

app.get("/api/notes/:categoryName", function (req, res) {
    var categoryName = req.params.categoryName;

    data.getNotes(categoryName, function (err, notes) {
        if (err) {
            res.send(400, err);
        } else {
            res.set("Content-Type", "application/json");
            res.send(notes.notes);
        }
    });
});

What's the deal?