NHibernate SchemaExport无法删除表...有时候

I'm using NHibernate for the DAL of my application, and in particlular NHibernate's SchemaExport function to drop/recreate my database schema before the execution of unit tests. The issue I'm having is that when I run the unit tests and execute SchemaExport one of my tables fails to drop every second time. This would indicate to me that there is some kind of foreign key issue preventing SchemaExport dropping my table - but I can't figure it out. My schema is very simple - A person table, an Address table and a PersonAddress table to support the many-to-many relationship between the two.I'm using NHibernate for the DAL of my applicat