c# – 无法使用Nhibernate为SQL Server CE创建架构

Fluently.Configure()
            .Database(MsSqlCeConfiguration.Standard
            .ConnectionString(c => c.Is("Data Source=" + file))
            .Dialect<NHibernate.Dialect.MsSqlCeDialect>()
            .Driver<NHibernate.Driver.SqlServerCeDriver>()
            .ShowSql())
            .Mappings(m => m.FluentMappings.AddFromAssemblyOf<NHibernateSessionFactory>())
            .ExposeConfiguration(BuildSchema)
            .BuildSessionFactory();  

private static void BuildSchema(Configuration config)
    {
       // new SchemaExport(config).Drop(false,true);
        //new SchemaExport(config).Create(true,true);

         //If DB File does not exists,create it.
        if (!File.Exists(file))
        {
            Directory.CreateDirectory(Path.GetDirectoryName(databaseFileName));
            SqlCeEngine engine = new SqlCeEngine("Data Source="+ file);
            engine.CreateDatabase();
            // this NHibernate tool takes a configuration (with mapping info in)
            // and exports a database schema from it
            new SchemaExport(config).Execute(false,true,false);
            //FormulasDAO.AddDefaultFormulaCollection();
        }
        else
        {
            new SchemaUpdate(config).Execute(false,true);
        }
    }

我有这样的例外

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

内在的例外是

The IDbCommand and IDbConnection implementation in the assembly
System.Data.SqlServerCe could not be found. Ensure that the
assembly System.Data.SqlServerCe is located in the application
directory or in the Global Assembly Cache. If the assembly is in
the GAC,use element in the application
configuration file to specify the full name of the assembly.

帮助解决这个问题.