Nhibernate does not work after upgrade to version 2.1.2

Question

I recently changes my NHibernate implementation from Version 2.1.0 to 2.1.2. For lazy loading I used the LinFu implementation using : NHibernate.ByteCode.Linfu.

Since I changed to the newest version I got the following error:

 [SecurityException: That assembly does not allow partially trusted callers.]
  NHibernate.ByteCode.LinFu.ProxyFactory..cctor() +0

When debugging I came to the following error:

   at NHibernate.ByteCode.LinFu.ProxyFactory..ctor()
   at NHibernate.ByteCode.LinFu.ProxyFactoryFactory.BuildProxyFactory()
   at NHibernate.Tuple.Entity.PocoEntityTuplizer.BuildProxyFactoryInternal(PersistentClass class, IGetter getter, ISetter setter)
   at NHibernate.Tuple.Entity.PocoEntityTuplizer.BuildProxyFactory(PersistentClass persistentClass, IGetter idGetter, ISetter idSetter)
   at NHibernate.Tuple.Entity.AbstractEntityTuplizer..ctor(EntityMetamodel entityMetamodel, PersistentClass mappingInfo)
   at NHibernate.Tuple.Entity.PocoEntityTuplizer..ctor(EntityMetamodel entityMetamodel, PersistentClass mappedEntity)
   at NHibernate.Tuple.Entity.EntityEntityModeToTuplizerMapping..ctor(PersistentClass mappedEntity, EntityMetamodel em)
   at NHibernate.Tuple.Entity.EntityMetamodel..ctor(PersistentClass persistentClass, ISessionFactoryImplementor sessionFactory)
   at NHibernate.Persister.Entity.AbstractEntityPersister..ctor(PersistentClass persistentClass, ICacheConcurrencyStrategy cache, ISessionFactoryImplementor factory)
   at NHibernate.Persister.Entity.SingleTableEntityPersister..ctor(PersistentClass persistentClass, ICacheConcurrencyStrategy cache, ISessionFactoryImplementor factory, IMapping mapping)
   at NHibernate.Persister.PersisterFactory.CreateClassPersister(PersistentClass model, ICacheConcurrencyStrategy cache, ISessionFactoryImplementor factory, IMapping cfg)
   at NHibernate.Impl.SessionFactoryImpl..ctor(Configuration cfg, IMapping mapping, Settings settings, EventListeners listeners)
   at NHibernate.Cfg.Configuration.BuildSessionFactory()
   at MyApplication.SessionManager..ctor() in C:\Projects\MyApps\MyApplication\SessionManager.cs:line 75

Is this because of the usage of NHibernate.ByteCode.LinFu? What can I do about it to make the application work again?