I have a BO with a User Defined Field. All works ok if I have ShowDeletedRows to false. (I am also not updating Deletedrows immediately)

If I set ShowDeletedRows to true, I get a DeletdRowInaccessibleException when I try to delete a row, and it is happening on the Get of the usder defined field. I  probably need to set the AllowDeletedRows to be swirched on for the field, and if this is the cause, how do I switch this on for a user defined field