In all honesty all anyone can do is guess why it's not working without a debug log
The very first thing to check - are you reloading the skin/restarting Kodi after making any changes to the skin? If not, you need to.
The next thing to check is if Skin Shortcuts is building the menu - do you see the 'Building menu' notification? If not, then the script either isn't being called correctly or is failing at a very early stage.
If you're not seeing it, next I would check how you've setup your development version of Estuary (or are you modding the version bundled directly with Kodi?) - if you haven't, I'd recommend copying it to the users addon folder, and changing the name and id in addon.xml. Then restart Kodi, enable your version of the skin in the addon browser and switch to it. People in this part of the forum will be happy to help you get set up with this sort of thing, but you may need to look at other posts in the area, or post a new thread for help.
After that get yourself a debug log - with the scripts own debug logging option enabled in addition to Kodi's (Settings > Add-Ons > Manage Dependancies) - that will confirm whether the script is being called to write the menu, and show any issues it may be having in doing so.