Not Strengthening Lessons

[J.D.Eckstrom]

I try to keep all my lessons gold: first thing each day I go through and find the ones that have sunk to 4/5 and refresh those. Today I'm having trouble. I have done one lesson (Swedish: Passive Participles) three times, have gotten XP for each time, but it is still 4/5. I have done another lesson twice (Swedish: Science) with the same results. On the first lessons, I did it three times without a mistake. Why is it still at 4/5? Help, please!