Virtual properties in SequelizeJS do not work

I have following schema in SequelizeJS:

var moment = require('moment');
module.exports = function(sequelize, DataTypes) {
var Account = sequelize.define('Account', {
    suspended: {
        type: DataTypes.BOOLEAN,
        defaultValue: false
    }
}, {
    getterMethods: {
        trialDaysLeft: function() {
            return 5;
        }
    },
         tableName: 'accounts'
});
    return Account;
};

I want to get trialDaysLeft when I call account.trialDaysLeft property.

I am getting

TypeError: Property 'trialDaysLeft' of object [object Object] is not a function

Where am I wrong?