haakaa fail??

I don’t produce much to start with but bought a haakaa to try to get an extra 2oz while night breastfeeding for daycare the next day (along w the 3-4 I get from pumping while at work). Was going well for about 4 weeks and then just all of a sudden stopped working. I can feel my opposite (non-feeding) breast is full but no let down happens for haakaa collection?!? What is wrong? Can I do something to correct this? I give a few pumps after attaching to stim nipple but still no (or VERY little) letdown. 😩 help!