There is something work in relation between Employee and Cash Boxes.
e = Employee.first
Employee Load (0.5ms) SELECT * FROM `employees` LIMIT 1
=> #<Employee id: 1, employee_category_id: 1, employee_number: "admin", joining_date: "2011-05-18", first_name: "Admin", middle_name: nil, last_name: "Employee", gender: nil, job_title: nil, employee_position_id: 1, employee_department_id: 1, reporting_manager_id: nil, employee_grade_id: 1, qualification: nil, experience_detail: nil, experience_year: nil, experience_month: nil, status: true, status_description: nil, date_of_birth: "2010-05-18", marital_status: nil, children_count: nil, father_name: nil, mother_name: nil, husband_name: nil, blood_group: nil, nationality_id: 76, home_address_line1: nil, home_address_line2: nil, home_city: nil, home_state: nil, home_country_id: nil, home_pin_code: nil, office_address_line1: nil, office_address_line2: nil, office_city: nil, office_state: nil, office_country_id: nil, office_pin_code: nil, office_phone1: nil, office_phone2: nil, mobile_phone: nil, home_phone: nil, email: nil, fax: nil, photo_filename: nil, photo_content_type: nil, photo_data: nil, created_at: "2011-05-19 04:17:23", updated_at: "2011-05-19 04:17:23">
e.cashboxes
NoMethodError: undefined method `cashboxes' for #<Employee:0xb62a2338>
from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.11/lib/active_record/attribute_methods.rb:260:in `method_missing'
from (irb):72