Problem with running rake on production

gistfile1.txt

#-----lib/tasks/import.rake------#

# require File.expand_path(File.dirname(__FILE__) + '../../../app/models/application_record.rb')
# require File.expand_path(File.dirname(__FILE__) + '../../../app/models/invoice.rb')
# require File.expand_path(File.dirname(__FILE__) + '../../../app/models/installment.rb')
# require File.expand_path(File.dirname(__FILE__) + '../../../app/models/seller.rb')
# require File.expand_path(File.dirname(__FILE__) + '../../../app/models/payer.rb')
# require File.expand_path(File.dirname(__FILE__) + '../../../app/models/operation.rb')
# require File.expand_path(File.dirname(__FILE__) + '../../../app/services/legacy_importation.rb')

namespace :import do
  desc "Given the path of a excel spreadsheet exported from Smart it will import paid invoices "
  task :paid_invoices, [:path] do |t, args|
    # Rails.application.eager_load!
    path = args.path
    LegacyImportation.new.paid_invoices_importation(path)
  end

  desc "Given the path of a excel spreadsheet exported from Smart it will import opened invoices "
  task :opened_invoices, [:path] do |t, args|
    # Rails.application.eager_load!
    path = args.path
    LegacyImportation.new.opened_invoices_importation(path)
  end
end

#--------on terminal--------#

# works fine
rake import:opened_invoices\[lib/xlsx_reader/titulos_abertos_biort.xlsx\] 

# throw us an error: "uninitialized constant"
heroku run rake import:opened_invoices\[lib/xlsx_reader/titulos_abertos_biort.xlsx\]