Fluent NHibernate automap configuration throwing vague error

I'm trying out the automapping capability of Fluent NHibernate, and the same code that worked with explicit ClassMap configurations is failing when building the SessionFactory when I try to move it to automapping.

Here's the code:

public static ISessionFactory GetSessionFactory()
{
    if (_sessionFactory == null)
    {
        _sessionFactory = Fluently.Configure()
            .Database(MsSqlConfiguration.MsSql2008.ConnectionString(c => c.FromConnectionStringWithKey("DB")))
            // It works with the following:
            // .Mappings(m => m.FluentMappings.AddFromAssemblyOf<Customer>())
            // It fails with this:
            .Mappings(m => m开发者_JAVA技巧.AutoMappings.Add(AutoMap.AssemblyOf<Customer>()))
            .BuildSessionFactory();

    return _sessionFactory;
}

The error I get is:

An invalid or incomplete configuration was used while creating a SessionFactory. Check PotentialReasons collection, and InnerException for more detail.

I get Count = 0 for PotentialReasons and the inner exception is the same as above.

The stacktrace refers to:

at FluentNHibernate.Cfg.FluentConfiguration.BuildSessionFactory() in d:\Builds\FluentNH-v1.x-nh3\src\FluentNHibernate\Cfg\FluentConfiguration.cs:line 113

It seems like I've tried everything to get it to work, and the closest I came was to have the initialization work only to get a Could not find persister for... error when I tried to use the session, and I don't even remember how I was able to get that to happen.

I'm using the build #694 with NHibernate 3.0, SQL 2008 database. Any ideas what I'm doing wrong?

This was a dumb error that Aliostad's comment helped me find. I had an enum type that was stored as an integer in the database, and NHibernate was choking on that. I added an EnumConvention to the setup like this:

_sessionFactory = Fluently.Configure()
    .Database(MsSqlConfiguration.MsSql2008.ConnectionString(c => c.FromConnectionStringWithKey("DB")))
    .Mappings(
        m =>
        m.AutoMappings.Add(AutoMap.AssemblyOf<Customer>(new AutomapConfiguration()).Conventions.
                               Setup(c =>
                                         {
                                             c.Add<PrimaryKeyConvention>();
                                             c.Add<EnumConvention>();
                                             c.Add<CascadeAllConvention>();
                                         })
                               .IgnoreBase(typeof (EntityBase<>))
                               .OverrideAll(map => map.IgnoreProperty("IsValid"))))
    .BuildSessionFactory();

Here's that enum convention:

public class EnumConvention : IUserTypeConvention
{
    public void Accept(IAcceptanceCriteria<IPropertyInspector> criteria)
    {
        criteria.Expect(x => x.Property.PropertyType.IsEnum);
    }

    public void Apply(IPropertyInstance target)
    {
        target.CustomType(target.Property.PropertyType);
    }
}