nHibernate and Oracle Mapping Issue

Question

I am using nHibernate with Oracle, using Oracle's ODP implementation.

http://tiredblogger.wordpress.com/2008/11/07/using-oracle-odp-with-nhibernate-from-a-c-class-library/

This is pretty much working but then I got this error:

Unable to cast object of type 'Oracle.DataAccess.Client.OracleConnection' to type 'System.Data.Common.DbConnection'.

Which I fixed by adding this mapping:

<property name="hbm2ddl.keywords">none</property>

from: http://fabiomaulo.blogspot.com/2009/06/auto-quote-tablecolumn-names.html

However now I get this error:

NHibernate.Cfg.HibernateConfigException : An exception occurred parsing configuration :The 'name' attribute is invalid - The value 'hbm2ddl.keywords' is invalid according to its datatype 'String' - The Enumeration constraint failed. ----> System.Xml.Schema.XmlSchemaValidationException : The 'name' attribute is invalid - The value 'hbm2ddl.keywords' is invalid according to its datatype 'String' - The Enumeration constraint failed.

Any ideas?