Error trying to save DateTime object in DataBase

Hello I am having trouble with datetime objects, I had the "good" idea
of making a form, asking for the parameters of DateTime and then give
this object to the Database, apparently this is not the way.

I have this error: wrong number of arguments (2 for 1)

And this is what I tried:

I have a model like this
      datetime :when
      string :where
A view like this
<% form_tag exams_path do %>
  <p>
    Place:<br/>
    <%= text_field_tag 'place' %>
  </p>
  <p>
  Date and Hour:<br/>
  Day: <%= text_field_tag 'day', nil, :size => 4, :maxlength => 2
%><br/>
  Month: <%= text_field_tag 'month',nil, :size => 4, :maxlength => 2
%><br/>
  year: <%= text_field_tag 'year', nil, :size => 4, :maxlength => 4
%><br/>
  Hour: <%= text_field_tag 'hour', nil, :size => 4, :maxlength => 2
%><br/>
  Minute: <%=text_field_tag 'minute',nil, :size => 4, :maxlength =>
2%><br/>
  </p>
  <p>
    <%= submit_tag 'Save' %>
  </p>
<% end %>
And a controller like this
    @fecha = DateTime.new(params[:year].to_i, params[:month].to_i,
params[:day].to_i, params[:hour].to_i, params[:minute].to_i)
    @exam = Exam.new(DateTime.now, params[:place])
    if @exam.save
      redirect_to exams_path
    else
      render :action => 'new'
    end

Thanks for your help.

And a controller like this
@fecha = DateTime.new(params[:year].to_i, params[:month].to_i,
params[:day].to_i, params[:hour].to_i, params[:minute].to_i)
@exam = Exam.new(DateTime.now, params[:place])

Assuming Exam is an activerecord object you should be passing a hash
of attributes (eg :foo => params[:foo], :bar => params[:bar], whereas
you are passing 2 arguments

Fred

I didn't understand your solution Fred, thanks a lot for your post. I
solved my problem by saving in the database each element of the date as
integers, then I read this elements and I build my DateTime element.

I was just saying that you've passed two parameters to Exam.new rather
than a hash of options.
Fred