Can't edit another language pages from Admin panel

Hello, friends!
I have set up multilanguage. Everything works fine.
But when I open a page for editing in the Admin panel, and try to switch the language to non-primary on the right with the button, then I have the same page for editing: in primary language.
What am I configured incorrectly?
Thank you!

P. S. It's about Admin panel plugin.

@jooru, When you have saved the page in the primary language, you can continue editing the page in the other language and then save it in the other supported language by clicking on 'Save' and choose 'Save as ... '