One record too many stored, with NULL. Why?

Hi, I have a form, that after submit saves data in 2 different tables.
It works fine, only in the member-table there is an extra record added,
each time the user submits data, with in the rubric_idfield NULL. I
checked the parsed data, and they are fine, no extra anything. Should
be simple but I cannot pinpoint it. Please, if you could spare some
time...

Code:

Action =
Combination.transaction do
    @members.combination = @combination
    @combination.add_rubrics(@rubrics)
    @combination.save
    @members.save
  end

add_rubrics =

def add_rubrics(rubrics)
  rubrics.items.each do |item|
    li = Member.new_rubric(item)
    members << li
  end
end

new_rubric(item)=

def self.new_rubric(item)
   li = self.new
   li.rubric_id = item.id
   li
  end
I'm convinced it has to be here, but I don't know why it happens.

Hi Fred, thanks for replying. Unjfortunately, I don't think that is the
case. The rubrics all come from a predefined list, so there is no
saving involved before @rubrics is created. That is what makes is so
wierd for me.

Frederick Cheung schreef:

Yep.
Iknow there must be a season for this extra record, and it's the first
I've ever seen this. I even restarted my working sytem a few times (Mac
OSX 4.8; MAMP, Locomotive, Textmate), with no difference. That's why
I'm so... flabbergasted. (Like that word)

Frederick Cheung schreef: