Ajax request with GET works but not with POST

When I make an ajax request with POST method and the below route:

router.post('/shows', function(req, res){
        model.find({}, function(sent, recieved){
            res.contentType('json');
            res.send({ some: JSON.stringify({response:'json'}) });
        });
    });

I get error 500,

When I use ajax request with GET method and the below route

router.get('/shows', function(req, res){
    model.find({}, function(sent, recieved){
        res.contentType('json');
        res.send({ some: JSON.stringify({response:'json'}) });
    });
});

it works.

I make an ajax request with jQuery:

 $.ajax({
           type: "POST",
           url: "/shows",
           dataType:"json"
       })
          .done(function( done ) {
                        console.log(done)
          });

My console says:

express deprecated res.send(status, body): 
Use res.status(status).send(body) instead node_modules/kraken-js/middleware/500.js:27:17

Any ideas why my post route is not returning data properly?