Why is this class method returning 'null'?

I have a class in my Selenium framework that is responsible for getting a fresh driver object and passing it to the tests for use.

But for some reason, it's returning a null error and I can't figure out why.

Here is the class:

DriverManager

private WebDriver driver;

    public WebDriver getDriver() {
        WebDriverFactory factory = new WebDriverFactory();
        driver = factory.CreateBrowser(CHOSEN_BROWSER);
        return driver;
    }

My Factory class:

public WebDriver CreateBrowser(BrowserType browser)
    {
        switch(browser) {
            case Chrome:
                return createChromeDriver();
            case Firefox:
                return createFirefoxDiver();
            case InternetExplorer:
                return createInternetExplorerDriver();
            default:
                System.out.println("Invalid browser type");
                return null;
        }
    }

My tests where I am creating an instance of the DriverManager:

BaseTest:

public DriverManager driverManager;
    public WebDriver driver;

@Before

public void CreateDriver()
{
    driver = driverManager.getDriver();
    Pages.init(driver);
    Logging.info("TEST STARTING:  " + name.getMethodName());
}

But as soon as it hits the first line in the CreateDriver method. I recieved a null pointer error and the tests fail with a NullPointerException.