NHibernate join table criteria and alias problem

Question

Hi all. I am trying to query a table that looks like this

CatalogProduct

• CatalogId - FK to Catalog
• ProductId - FK to Product

The product table has a ParentProductId which is an FK to itself.

using the NHibernate criteria API, i need to get a list of CatalogProducts where the CatalogId is and the ProductId is the Product.ParentProductId (not Product.ProductId).

This is my query, which gives me exceptions:

 ICriteria criteria = session.CreateCriteria<CatalogProduct>()
                    .CreateAlias("Product", "pr")
                    .CreateAlias("pr.ParentProduct","ppr")
                    .Add(Restrictions.Eq("ppr.ProductId", productId))
                    .Add(Restrictions.Eq("Catalog.CatalogId", catalogId));

InnerException = {"The multi-part identifier \"ppr2_.ProductId\" could not be bound."}