I have this very annoying error that is not telling much about where I should look to fix the problem.

```
undefined method `' for #<Conference:0x00000112a617c0>

```

The error is occurring when I want to save a new Conference record via the Rails Admin

The code is the following:

**Conference class:**

```
class Conference < ActiveRecord::Base

  include TheDate

end

```

**module TheDate:**

```
module TheDate
  extend ActiveSupport::Concern

   included do
     has_many :meeting_dates, as: :dateable, dependent: :destroy
     accepts_nested_attributes_for :meeting_dates, :allow_destroy => true
   end
end

```

**MeetingDate class:**

```
class MeetingDate < ActiveRecord::Base

  belongs_to :dateable, polymorphic: true
  belongs_to :conference, -> { where(:'event_dates.dateable_type' => 'Conference') }, foreign_key:   :dateable_id
  belongs_to :course, -> { where(:'event_dates.dateable_type' => 'Course') }, foreign_key: :dateable_id
  belongs_to :meeting, -> { where(:'event_dates.dateable_type' => 'Meeting') }, foreign_key: :dateable_id

end

```

Would you know what could cause it ? Since there is no method name in the error, I have no idea where to look...

Thanks