title: Obscure NHibernate/Fluent NHibernate error
body: <p>I've been encountering the following error when trying to build a 
  session factory:</p>
  
  <pre><code>PersistenceTests.Can_Map_Orders_To_Database : Failed 
  System.IndexOutOfRangeException: Index was outside the bounds of the 
  array. 
  at NHibernate.Mapping.Column.set_Name(String value) 
  at NHibernate.Cfg.XmlHbmBinding.ClassBinder.BindColumns(XmlNode node, 
  SimpleValue model, Boolean isNullable, Boolean autoColumn, String 
  propertyPath) 
  at NHibernate.Cfg.XmlHbmBinding.ClassBinder.BindColumnsOrFormula 
  (XmlNode node, SimpleValue simpleValue, String path, Boolean 
  isNullable) 
  at NHibernate.Cfg.XmlHbmBinding.ClassBinder.BindSimpleValue(XmlNode 
  node, SimpleValue model, Boolean isNullable, String path) 
  at 
  NHibernate.Cfg.XmlHbmBinding.CollectionBinder.BindCollectionSecondPass 
  (XmlNode node, Collection model, IDictionary`2 persistentClasses) 
  at 
  NHibernate.Cfg.XmlHbmBinding.CollectionBinder.&lt;&gt;c__DisplayClassd.&lt;AddCollec tionSecondPass&gt;b__c 
  (IDictionary`2 persistentClasses) 
  at NHibernate.Cfg.Configuration.SecondPassCompile() 
  at NHibernate.Cfg.Configuration.BuildSessionFactory() 
  at FluentNHibernate.Cfg.FluentConfiguration.BuildSessionFactory() in c: 
  \Code Samples\NHibernate\Fluent Nhibernate - Trunk\src\FluentNHibernate 
  \Cfg\FluentConfiguration.cs: line 94 
  FluentNHibernate.Cfg.FluentConfigurationException: An invalid or 
  incomplete configuration was used while creating a SessionFactory. 
  Check PotentialReasons collection, and InnerException for more detail. 
  at FluentNHibernate.Cfg.FluentConfiguration.BuildSessionFactory() in c: 
  \Code Samples\NHibernate\Fluent Nhibernate - Trunk\src\FluentNHibernate 
  \Cfg\FluentConfiguration.cs: line 99 
  at FluentNHibernate.SessionSource..ctor(FluentConfiguration config) in 
  c:\Code Samples\NHibernate\Fluent Nhibernate - Trunk\src 
  \FluentNHibernate\SessionSource.cs: line 38 
  at 
  FluentNHibernate.Testing.SingleConnectionSessionSourceForSQLiteInMemoryTest ing..ctor 
  (FluentConfiguration config) in c:\Code Samples\NHibernate\Fluent 
  Nhibernate - Trunk\src\FluentNHibernate\Testing 
  \SingleConnectionSessionSourceForSQLiteInMemoryTesting.cs: line 15 
  at Core.Infrastructure.Data.NHibernate.Tests.PersistenceTests.SetUp() 
  in PersistenceTests.cs: line 26
  </code></pre>
  
  <p>I'm working against the FNH trunk and NH 2.0.1. Funny thing is I am 
  able to compile my mappings (via AutoPersistenceModel.CompileMappings) 
  and write them to the file system successfully - FNH doesn't complain. 
  It is only when attempting to build the session factory that 
  everything goes kaboom with the not very helpful error message above. 
  Anyone got any ideas?</p>