Hi. I'm using the Ruby SOAP4r library with the Enterprise portal to try to add a new Opportunity. I create a new Opportunity object and add all the fields that SalesForce appears to require:

opp = Opportunity.new
class << opp
  attr_accessor :accountId, :amount, :name, :closeDate, :stageName
end

opp.accountId = the_account
opp.amount = "3.14"
opp.name = "Test from script"
opp.closeDate = "2005-8-25"
opp.stageName = "Closed Won"

binding.create(Create.new([opp]))

But I consistently see the error message "common.exception.ApiException: Must send a concrete entity type. (SOAP::FaultError)". I don't get it. What could be more concrete than an Opportunity? How can I find out what piece of information SForce is missing? Should I add more fields? Which ones?

Before you ask, yes, I've regenerated my WSDL files and rerun wsdl2ruby.