Python/Tornado - call to classmethod

Given this simple code where I declare a class and a functions inside it. In the main I try to call the function but the call is not made. I don't get any error but if I put a print in order to know if the call has happened nothing occurs.

models

class Balance(Document):
    gross_balance = FloatField(required=True, min_value=0, default=0)

    @classmethod
    def createBalance(cls, gross_balance):
        result = yield Balance.objects.create(gross_balance = gross_balance)
        result.save()
    @classmethod
    def sayHi(cls):
        print "Hi there"

main

from models import Balance

class CreateBalanceHandler(tornado.web.RequestHandler):

@tornado.gen.coroutine
def post(self):
    gross_balance = self.get_argument('gross_balance')
    Balance.createBalance(gross_balance)
    Balance.sayHi()
    self.redirect('/query/{}'.format(gross_balance))

What am I doing wrong? The sayHi function show its print but there's no reaction with createBalance.

Decorate createBalance with gen.coroutine to run it on ioloop. To wait until balance is created invoke it like yield Balance.createBalance() in RequestHandler

models

class Balance(Document):
    gross_balance = FloatField(required=True, min_value=0, default=0)

    # classmethod must be the most outter decorator (as well as staticmethod)

    @classmethod
    @tornado.gen.coroutine
    def createBalance(cls, gross_balance):
        result = yield Balance.objects.create(gross_balance = gross_balance)
        # AFAIR save returns future and also should be yielded
        # yield. result.save()
        result.save()

    @classmethod
    def sayHi(cls):
        print "Hi there"

main

from models import Balance

class CreateBalanceHandler(tornado.web.RequestHandler):

    @tornado.gen.coroutine
    def post(self):
        gross_balance = self.get_argument('gross_balance')
        yield Balance.createBalance(gross_balance)
        Balance.sayHi()
        self.redirect('/query/{}'.format(gross_balance))

Note: As I mentioned in snippet's comment, in motorengine the Document.save returns Future and probably you want to yield it as well, to wait until it has finished.