Have you moved your EndNote X6.app file? If so, this would cause the program problems recognizing the installed Styles. The EndNote X6.app (the extension may be hidden) Application File needs to be inside the Applications > EndNote X6 folder. You can create an Alias to the file, but moving it will cause issues. If the file is present, you may need to reset your Style Favorites. To do this, click on the Edit menu > Output Styles > Open Style Manager. Check the Styles you want listed as Favorites then close the Style Manager. Quit and restart both EndNote and Pages to see Styles in Pages.