Problems with fixtures and HABTM

I have:

treatments.yml

treatment3:   id: 3   code: T3   description: "Desarrollo de una política de seguridad"   reduction: 0.3   document: "D01_Politica_Seguridad"   account_id: 1   soa_lines: soa_line3 treatment4:   id: 4   code: T1   description: "Inclusión en el mantenimiento de los sistemas un chequeo de la seguridad del navegador en uso."   reduction: 0.1   document: "D10_Mantenimiento_Equipos.docx"   account_id: 2   soa_lines: soa_line4

and:

soa_lines.yml

soa_line3:   account_id: 1   id: 3   justification: "La política de seguridad es fundamental para el funcionamiento del sistema"   control_id: 3   applicability: true soa_line4:   account_id: 2   id: 4   justification: "Es necesario proteger las transacciones en línea que realiza la organización"   control_id: 1   applicability: true   treatments: treatment4

And both models have:

treatment.rb

has_and_belongs_to_many :soa_lines

soa_line.rb

has_and_belongs_to_many :treatments

But when I try to access to treatment.soa_lines it returns nothing:

  test "successful treatment modification" do     treatment = treatments(:treatment4)

    puts "Id", treatment.id     puts "Code", treatment.code     puts "Description", treatment.description     puts "Reduction", treatment.reduction     puts "Account", treatment.account.name     puts "Soa Lines", treatment.soa_lines

All puts return correct values but treatment.soa_lines is

What I'm doing wrong? What can I check to correct this?

The problem was that if you want to use the name convention for defining relationships like in:

treatments: treatment4

The treatment fixture cannot have an id attribute. Ids should be managed by Rails in this case.