activerecord-sqlserver-adapter nvarchar datatype length

I've recently installed this adapter in hope that I can work with utf-8 encoding using the SQL Server nvarchar data type. I've installed and followed the steps detailed at this uri: http://github.com/adzap/rails-sqlserver-adapter/tree/master

I have this following migration class definition: class CreateContacts < ActiveRecord::Migration     def self.up           create_table :contacts do |t|             t.column :organization_id, :integer, :null=>false             t.column :first_name, :nvarchar, :limit=>10, :null=>false             t.column :last_name, :nvarchar, :null=>false             t.column :title, :string             t.column :contact_type_id, :integer, :null=>false             t.column :fax, :string             t.timestamps         end     end

    def self.down         drop_table :contacts     end end

When I look at the generated table definition, the first_name column created has a length of 2 rather than 10 as specified by the :limit parameter. In fact all of the columns of type :nvarchar get a length of 2. If I try what the web site documentation has, namely:

t.column :body2_utf8, :nvarchar_max # Creates nvarchar(max) or in my case: t.column :first_name, :nvarchar_max, :null=>false

I get an error that says: DBI::DatabaseError: Execute     OLE error code:80040E14 in Microsoft OLE DB Provider for SQL Server       Column, parameter, or variable #3: Cannot find data type nvarchar_max.     HRESULT error code:0x80020009

What is the correct way to set the maximum length of the nvarchar data type?