Error Description
The Joomla language switcher will not be displayed. There isn´t any dropdown, which allows to change the language. Moreover the language flag isn´t displayed in the menu tab:
Reason
The definiton of the standard for the corresponding menu page is missing.
A screenshot of the menu entry:
Debugging
Click the star-symbol to select the default page. If the default page is defined, there will be a flag of the country in the menu tab next to the name.
Note: This have to be done for all other menus with different languages, too.
The result should be look like this: