Menu item won't get into open directory when clicking the arrow buttons found at the bottom of the menu browser

[rsevero]

I'm trying to move a menu item inside a directory using the process described at https://wiki.smdavis.us/doku.php?id=menulibre_usage#rearranging_the_menu :

"Rearranging the Menu

Clicking the arrow buttons found at the bottom of the menu browser will move the currently selected menu item. If the directory above or below is expanded, the menu item will be moved into that entry. In this way, menu items can be easily placed into subdirectories."

Unfortunately my menu item never goes inside the opened directory, even after being closed and reopened. Nor it goes inside the directory if it's closed.

In brief: I can't put my menu item inside a directory at all.

I'm using MenuLibre 2.0.6 on Xubuntu 15.04

Please let me know if there is any extra info necessary.