Selenium Webdriver Python AttributeError type object has no attribute

I am getting the following error in my Python Selenium Webdriver script.

Error
Traceback (most recent call last):
  File "C:\Webdriver\ClearCore 501\TestCases\VariablesPage_TestCase.py", line 87, in test_add_variables
    variablesPage = projectnavigator.select_projectNavigator_item("Variables") # Select the Variables link from the left hand Project Navigator, it returns the Variables page object
  File "C:\Webdriver\ClearCore 501\Menus\project_navigator.py", line 24, in select_projectNavigator_item
    variables_projectnavigator_link = self.driver.find_element(*MainPageLocators.variables_project_navigator_link2).click()
AttributeError: type object 'MainPageLocators' has no attribute 'variables_project_navigator_link2'

I think it is because the class has not been instantiated. You cannot access a member variable without an instance of the class. I think I have instantiated my class like this:

projectnavigator = project_navigator.ProjectNavigatorPage(self.driver)

I do not know why I am getting the error.

My code snippet is as follows:

class ProjectNavigatorPage

    # This class defines the methods for the the ClearCore left hand project navigator
# i.e. Selecting the Data Objects, Datasets, Variables, Feeds, Mappings, Data Previews etc

import time
from Pages.base import BasePage
#from Pages.login import LoginPage
from Pages.admin import AdministrationPage
from Locators.locators import MainPageLocators
from Pages.variables import VariablesPage

class ProjectNavigatorPage(BasePage):

    # Select an item from the Project Navigator  e.g. Data Objects tab, Datasets, Variables etc
    def select_projectNavigator_item(self, menu_item):
        if menu_item == "Data Objects":
            #LoginPage.clickAdministration()
            #self.clickAdministration(self)
            pass
        elif menu_item == "Datasets":
            pass
        elif menu_item == "Variables":
            variables_projectnavigator_link = self.driver.find_element(*MainPageLocators.variables_project_navigator_link2).click()
            return VariablesPage(self.driver)

        elif menu_item == "Feeds":
            pass
        elif menu_item == "Mappings":
            pass
        elif menu_item == "Data Previews":
            pass

class VariablesPage_TestCase

    # This class defines the tests for the the Variables page.  e.g. Add a variable, Name, Address, DOB

import unittest
import time
import datetime
from selenium import webdriver
from Locators import locators, Globals
from Locators import element
from Menus import project_navigator
from Pages import login
from Pages import admin
from Pages import main_dashboard
from Pages import data_objects, variables
from Menus import toolbar
from Pages import datamaps
from Pages import datasets
from Pages import base
from Utilities import Utilities
from Pages import data_previews
from Pages import data_objects_saved_page
import datetime
from selenium.webdriver.support.ui import Select

class VariablesPage_TestCase(unittest.TestCase):

    def setUp(self):
        #webdriver.DesiredCapabilities.FIREFOX["unexpectedAlertBehaviour"] = "accept"
        webdriver.DesiredCapabilities.INTERNETEXPLORER["unexpectedAlertBehaviour"] = "accept"
        #self.driver = webdriver.Firefox()
        #self.driver = webdriver.Ie("C:\QA\Automation\Python_projects\Selenium Webdriver\IEDriverServer_Win32_2.45.0\IEDriverServer.exe")
        self.driver = webdriver.Ie(Globals.IEdriver_path)
        self.driver.get(Globals.URL_justin_pc)
        self.login_page = login.LoginPage(self.driver)
        self.driver.implicitly_wait(100)


    def test_add_variables(self):
        print "*** Test add Variables ***"
        data_dashboard_page = self.login_page.userLogin_valid(Globals.login_username, Globals.login_password)
        md = main_dashboard.MainDashboardPage(self.driver)
        #main_dashboard.MainDashboardPage.select_project_from_drop_down(self)
        md.select_project_from_drop_down()
        data_configuration_page = data_dashboard_page.click_data_configuration2() # Click Data Configuration from the Project Navigator
        #assert data_dashboard_page.is_Data_Configuration_pageDisplayed(), "Data Configuration Page not displayed"
        print "data_configuration_page.is_Data_Configuration_pageDisplayed()"
        #print data_dashboard_page.is_Data_Configuration_pageDisplayed()
        time.sleep(10)
        assert data_configuration_page.is_Data_Configuration_pageDisplayed(), "Data Configuration Page not displayed"
        if data_configuration_page.is_Data_Configuration_pageDisplayed() == True:
            pass
        else:
           print "ERROR - Data Configuration page is not displayed"
       # tool_bar = toolbar.ToolbarPage(self.driver)
        projectnavigator = project_navigator.ProjectNavigatorPage(self.driver)
        variablesPage = projectnavigator.select_projectNavigator_item("Variables") # Select the Variables link from the left hand Project Navigator, it returns the Variables page object

class Locators

    from selenium.webdriver.common.by import By

class MainPageLocators(object):
    usernameTxtBox = (By.ID, 'unid')
    passwordTxtBox = (By.ID, 'pwid')
    submitButton = (By.ID, 'button')

    # Data Configuration page
    DataConfiguration_button_xpath = (By.XPATH, '//div[. = "Data Configuration"]')
    data_config_elementTxt = (By.XPATH, '//span[contains(@title, "Data Configuration")][text()="Data Configuration"]')
    data_config_elementTxt2 = (By.XPATH, '//span[@title="Data Configuration"]')

    # Variables page
    variables_title_page_text = (By.XPATH, 'html/body/div[2]/div[2]/div/div[4]/div/div[2]/div/div[3]/div/div[5]/div/div[3]/div/div[4]/div/div[2]/div/div[2]/div/div/span') # This is the text beside the Add button (Variables)
    variables_project_navigator_link = (By.XPATH, '//span[@title="variables" and contains(text(), "variables")]')
    variables_projet_navigator_link2 = (By.XPATH, 'html/body/div[2]/div[2]/div/div[4]/div/div[2]/div/div[3]/div/div[5]/div/div[3]/div/div[2]/div/div/div/div/div/div/div[1]/div/div[2]/div/div[1]/div[3]/div[1]/div/div[2]/div/div[2]/span')
    variables_page_no_data_to_display_text = (By.XPATH, '//div[@class="gwt-Label absoluteLeft padding" and contains(text(), "No data to display")]') # This is the text where it says No data to display when you land on the variables page