ArgumentError (wrong number of arguments (given 0, expected 2))

[alegrria]

I have a test app on pixi and want to access its data via Rails app.
I configured the client as following:

PixiClient.configure do |config|
  config.endpoint = ENV["ENDPOINT_URL"]
  config.username = ENV["PIXI_USERNAME"]
  config.password = ENV["PIXI_PASSWORD"]
  config.wsdl     = "#{Rails.root}/config/pixi_client.wsdl"
end 

When i try to fullfil a SOAP request
response = PixiClient::Requests::GetInvoice.new(invoice_id).call in irb,
i get ArgumentError (wrong number of arguments (given 0, expected 2)).

Same request via SoapUI returns correct data.

I cannot get through this.