Some appium_lib functions don't work

Hello,
I’m doing android test on Appium with Ruby.
I have “undefined method” errors for a lot of appium_lib method and I don’t understand why.
I declare a appium driver like this :
capabilities = {
caps: {
‘appPackage’ => ‘com.myapp.demo’,
‘appActivity’ => ‘.MainActivity’,
‘platformName’ => ‘android’,
‘deviceName’ => ‘Android’
},
appium_lib: {
sauce_username: nil, # don’t run on Sauce
sauce_access_key: nil
}
}
@driver = Appium::Driver.new(capabilities).start_driver
@browser = Watir::Browser.new @driver
@browser.driver.manage.timeouts.implicit_wait = 30

I can see that some method are ok. As example :
@driver.hide_keyboard do what I want.
But I have “undefined method” when I’m doing “@driver.device_is_android?” or “@driver.driver_attributes
Maybe I’m not using the method the way I should ?
Thanks a lot guys

# appium specific driver with helpers available
@appium_driver = Appium::Driver.new @options
# standard selenium driver without any appium methods
@selenium_driver = @appium_driver.start_driver

Thanks a lot, it’s working !
I don’t get why I miss this crucial information…