Problems with attachments

Hello everybody

I have some problems with an attachments.

I have the next model

class Profile < ActiveRecord::Base

  belongs_to :user

  before_create :set_default_icon

  has_attached_file :icon, {
    :url => "/
system/:class/:attachment/:id/:style_:basename.:extension",
    :styles => {
      :big => Tog::Plugins.settings(:tog_social,
"profile.image.versions.big"),
      :medium => Tog::Plugins.settings(:tog_social,
"profile.image.versions.medium"),
      :small => Tog::Plugins.settings(:tog_social,
"profile.image.versions.small"),
      :tiny => Tog::Plugins.settings(:tog_social,
"profile.image.versions.tiny")
    }}.merge(Tog::Plugins.storage_options)

  has_attached_file :pdf, {
    :url => "/
system/:class/:attachment/:id/:style_:basename.:extension",
    :path => "/
system/:rails_root/:public/:profile/:pdfs/:id/:style/:basename.:extension"
  }.merge(Tog::Plugins.storage_options)

  validates_attachment_content_type :pdf, :content_type =>
[ 'application/pdf', 'application/msword',

'application/vnd.openxmlformats-
officedocument.wordprocessingml.document' ],
                                    :message => 'Asegurese que el
fichero tiene la extensión .pdf o .doc'

end

When i put validates_attachment_content_type :pdf ¿is obligatory that
i have to upload a file?

because if I only upload a photo then when i submit on my form fails
because i don't update a pdf.

Can anyone help me?

thanks.