The SubFields property and AddField method work as documented. The SubFields property is a comma-delimited list of field names which is set to "*" by default. "*" is standard SQL for all fields. AddField adds a field name to this list. If you call AddField when SubFields is set to "*", then it does nothing because adding a field to the list when it's already set for all fields would be redundant. If you set the SubFields property to a single field name or a comma-delimited list of field names, then call AddField, it will add that field to the list (see Kirk's example above).
