Issues Customizing ActiveRecord Error Messages

I have two issues with trying to customize error messages. I'm using
Rails 2.3.4 and Ruby 1.8.7.

The first issue has to do with basic error message interpolation.
As an example, I modified my en.yml file and added the following:

en:
  activerecord:
    errors:
      messages:
        blank: "Please fill in your {{attribute}}"

I have a simple model with a validates_presence_of :name

When I submit a form without filling out name, the error message shows
as "Name Please fill in your Name"
What am I doing wrong that causes "Name" to show up twice?
I feel like I am missing something basic, but looking at the Rails
I18n API (http://guides.rubyonrails.org/i18n.html) hasn't helped.

The second issue has to do with validations for nested attributes.

In my en.yml, I have the following which provides a value for
human_name on the class. (I removed the activerecord: errors:
messages: blank: code for this example.)

en:
  activerecord:
    models:
      adhoc_filter: "Filter"

In my adhoc_filter child model, I have a validates_presence_of :field

When I submit the form, the error message shows up as "Adhoc filters
field can't be blank" instead of "Filter field can't be blank"

I'm not sure if nested attribute errors will work the way I want them
to, but it would be nice.

Any advice on one or both of these issues is greatly appreciated.

As a follow up to the second issue, if I specify the error message as:

en:
  activerecord:
    errors:
      messages:
        blank: "-- {{attribute}} - {{model}}"

I see the following error: "Adhoc filters fields -- Adhoc filters
field -- Filter"

So the model human name is getting set correctly, but the child
attribute is getting concatenated with the non human-name of the model
with the child field.