Grasshopper

Hello everyone! I have a little problem going on with my Chansey. I have leveled her to 85 planning to go to level 90 and giving 10 rare Candies. When I turned 85 I disconnected during the evolving window. When I logged back in, it became a Blissey :/ Does that usually happen? With this post I would like to request to devole my Blissey into Chansey since I spent a huge amount of time to find and level this Pokemon up. I would really really appreciate if you can make this happen :) Thanks a lot!