I tried one of these out for about a week, and then decided that it was too stressful wondering if she was getting enough food. I don't have any insight into why yours may have died, but they do seem to be very prone to stress, as mine would just hide for about 95% of the time I saw her even after being in the tank for a week. I kept worrying she wasn't getting enough food, and I don't want to have to worry about my creatures all the time, so I just took her back to aquarium co-op, Cory was more than happy to take her back.
They look cool when they are happy and fanning, but in my opinion, they are not really a beginners' shrimp. not saying you are a beginner, but I definitely am, and I wish I would have picked a couple amano instead