Why doesn't ICriteria pass variable value to the withClause?

Question

I'm trying to restrict a left outer join with a simple restriction but it fails with an sql exception.

System.Data.SqlClient.SqlException: Must declare the scalar variable "@p1".

My ICriteria:

 var r = session.CreateCriteria<Parent>("p")
.CreateCriteria("p.Children", "c", NHibernate.SqlCommand.JoinType.LeftOuterJoin, Restrictions.Eq("c.Name", "John Doe"))
.List();

The desired SQL:

SELECT * FROM Parents p
LEFT OUTER JOIN Children c ON c.ParentID = p.ID AND c.Name = 'John Doe' 

Do I have to add the variable values in any way? The SQL generated by NHibernate is correct but the variable just isn't sent to the server.