debug this, if error exist, you see message in console and rollback is run, else ...
sequelize()
.transaction(function(t){
myModel.create({name: 'shawn'}).success(function(newModel) {
console.log('success1')
myModel.create({name: 'shawn'})
.success(function(newModel){
console.log('success2');
t.commit();
})
.error(function(err){
console.log('error2')
t.rollback();
});
}).error(function(err) {
console.log('error1')
t.rollback()
});
});