nhibernate auditing with events on update

Question

The following code works on insert but on update modifier is never set, any ideas why?

The code for pre-update is being run and correctly sets the state

Answer 1

Edit 1: This answer has been improved
Edit 2: It appears the the real cuase of the problem is dynamic-update set to true as found here however this solution still works for me.

The changes get saved when you update them in the OnFlushDirty function which is called earlier.

public override bool OnFlushDirty( object entity, object id, object[] currentState, object[] previousState, string[] propertyNames, NHibernate.Type.IType[] types )
{
    bool result = false;

    if (entity is IAuditable) {
        var auditable = (IAuditable)entity;

        Set( x => auditable.Modifier, propertyNames, auditable, currentState, SecurityManager.Identity );
        //Set( x => auditable.DateModified, args.Persister, auditable, args.State, TwentyClock.Now );

        result = true;
    }

    return result;
}