aptana安装完，直接导入一个ruby工程，之后运行一个ruby文件即报错

jianhlang

d:/softs/Ruby193/lib/ruby/gems/1.9.1/gems/selenium-webdriver-2.25.0/lib/selenium/webdriver/ie/server.rb:13:in `get': Unable to find standalone executable. Please download the IEDriverServer from http://code.google.com/p/selenium/downloads/list and place the executable on your PATH. (Selenium::WebDriver::Error::WebDriverError)
        from d:/softs/Ruby193/lib/ruby/gems/1.9.1/gems/selenium-webdriver-2.25.0/lib/selenium/webdriver/ie/bridge.rb:22:in `initialize'
        from d:/softs/Ruby193/lib/ruby/gems/1.9.1/gems/selenium-webdriver-2.25.0/lib/selenium/webdriver/common/driver.rb:35:in `new'
        from d:/softs/Ruby193/lib/ruby/gems/1.9.1/gems/selenium-webdriver-2.25.0/lib/selenium/webdriver/common/driver.rb:35:in `for'
        from d:/softs/Ruby193/lib/ruby/gems/1.9.1/gems/selenium-webdriver-2.25.0/lib/selenium/webdriver.rb:65:in `for'
        from d:/softs/Ruby193/lib/ruby/gems/1.9.1/gems/watir-webdriver-0.6.1/lib/watir-webdriver/browser.rb:35:in `initialize'
        from E:/rubyworkspace/tms_auto_test/login.rb:7:in `new'
        from E:/rubyworkspace/tms_auto_test/login.rb:7:in `login'
        from E:/rubyworkspace/tms_auto_test/order_check.rb:15:in `<main>'
如题  求助