如何用firefox驱动程序启动selenium

我尝试按照以下链接:http://www.seleniumhq.org/docs/03_webdriver.jsp

在SetUpTest:

protected IWebDriver driver;
protected ISelenium selenium;
[SetUp]
public void SetupTest()
{
    driver = new FirefoxDriver();
    selenium = new DefaultSelenium(
        "localhost", 
        4444,
        "*chrome",
        "http://localhost");
    selenium.Start();
    verificationErrors = new StringBuilder();
}

当这一行driver = new FirefoxDriver();执行时,我有这个错误:

Additional information: Cannot find a file named '***[Link to my project]\webdriver.xpi' or an embedded resource with the id 'WebDriver.FirefoxExt.zip'.

当我将其更改为时driver = new ChromeDriver();,它会打开firefox,但是虽然元素已经渲染,但它找不到元素.

如何让硒与firefox一起使用？