↓↑ What is this all about ? ↓↑
Your WordPress installation calls the plugin directory to fetch, if found, the latest version number of each plugin you're running. If your plugin is not found, WordPress will obviously never warn about a newer version when available.
To get your plugin found as expected, make sure that :
- its name in the readme.txt and the plugin header are the same
- its directory on your server reflects is the same than the plugin directory
- the plugin name reflects its directory name
See related blog post for more info and troubleshooting help.