Ruby on Rails

I have this strange behavior and I don't undertand why. Here is the thing:

I have this record in my payment model:

1.9.3p286 :019 > u.payment.last    Payment Load (0.3ms)  SELECT "payments".* FROM "payments" WHERE "payments"."user_id" = 10   => [#<Payment id: 37, bank_name: "Mercantil", plan: "Plan Uno", date: "2012-12-25", reference_number: "3452435", coupon: "", user_id: 10, created_at: "2012-12-25 21:56:12", updated_at: "2012-12-25 21:58:31", active_until: "2013-01-24">] 

As you can see, I have one record for my user: 10.

If I try to get the same information in my controller I don't get any exception, but

@user.payment.last.active_until

is empty, the same in the view.

For example if I try this in my view:

<%= @user.payment.last.active_until %>

I didn't get anything, is blank.

If I try this

<%= @user.payment %>

I got the same as my console

[#<Payment id: 37, bank_name: "Mercantil", plan: "Plan Uno", date: "2012-12-25", reference_number: "3452435", coupon: "", user_id: 10, created_at: "2012-12-25 21:56:12", updated_at: "2012-12-25 21:58:31", active_until: "2013-01-24">, #<Payment id: nil, bank_name: nil, plan: nil, date: nil, reference_number: nil, coupon: nil, user_id: 10, created_at: nil, updated_at: nil, active_until: nil>]

I really don't understand what happend here. Any help please.

Thanks in advance.

PD: The user could has many payments, but I need just the last.