Where did my perfume go?

So I got this tiny perfume bottle in HK but I believe you can find them in Daiso/Yokoyaya here in Vancouver. Anyway I put my Issey Miyake perfume in there and I pop it in my make up bag that I bring out with me. I have been neglecting it so one day I took it out and realized some of it was missing...! I guess maybe the lid doesn't screw tight enough or something.. or it just slowly evaporates... -_- I probably won't be putting perfume in there anymore.. I always forget about it when I'm out haha.