ActiveResource is not parsing JSON correct

It seems that ActiveResource is encapsulating the received object, adding a parent. This makes the received object having no known attributes.
I assume the problem is in the client and not the server. Simple examples from the console (as a client):

self.format = :xml

ruby-1.9.2-p0 > Link.first
=> #<Link:0x00000101c3d4d8 @attributes={"created_at"=>2010-10-25 14:49:16 UTC, "id"=>1, "name"=>"The link", "number"=>1, "updated_at"=>2010-10-25 14:49:16 UTC}, @prefix_options={}>

self.format = :json

ruby-1.9.2-p0 > Link.first
=> #<Link:0x00000100c67680 @attributes={"link"=>#<Link:0x00000100c66cf8 @attributes={"created_at"=>"2010-10-25T14:49:16Z", "id"=>1, "name"=>"The link", "number"=>1, "updated_at"=>"2010-10-25T14:49:16Z"}, @prefix_options={}>}, @prefix_options={}>

Simple examples from the browser (from the server):
http://localhost:3000/links/1.xml

<link>
  <created-at type="datetime">2010-10-25T14:49:16Z</created-at>
  <id type="integer">1</id>
  <name>The link</name>
  <number type="integer">1</number>
  <updated-at type="datetime">2010-10-25T14:49:16Z</updated-at>
</link>

http://localhost:3000/links/1.json

{"link":{"created_at":"2010-10-25T14:49:16Z","id":1,"name":"The link","number":1,"updated_at":"2010-10-25T14:49:16Z"}}