Do you click “I know all” every time you finish a lesson? If you do not do it, the lesson won’t be shown under your Activities.
@SanneT. Oh! You are very clever. 
I didn’t it before. Thank you very much. The system works perfect now.
As SanneT says, you must click the LingQ’d button in order for your statistics to update and for the lesson to show in your recent activity.