NHibernate.MappingException: No persister for: HelloNHibernate.vo.People

I am testing NHibnernate these days, but I get this kind of error message NHibernate.MappingException: No persister for: HelloNHibernate.vo.People

The cs name, package name are correct, but the console still report this error message.

Finally, I found out the root cause: all mapping files should be set Embedded Resource, then it can execture correctly.

right-click in XXX.hbm.xml->Properties->Build Action="Embedded Resource"