The Chicken (costume) goes out for the day.

My frustration with this costume is building and Halloween is still 5 days away. It started with her Halloween party, where she took off the costume I spent hours sneezing over (yes, I am allergic to pink dyed feathers) and insisted on wearing a very old torn Disney princess nightgown for the party. She worn the costume maybe 10 minutes.
Then today she was supposed to wear it to her gymnastic class. We had to make a deal she only had to wear it for two minutes, so her teacher could see it. She was sulky and pouting the entire two minutes. Grrrr, why did I spend all that time making this thing? Oh yeah, so she could wear it into TJ Maxx. Annie the girl who I had to beg to wear her costume just hours before, insisted on wearing it while we shop. Could someone please explain this to me? She wore the costume all through the store like the proud chicken I knew she could be, but when all the other kids are dressed up, she refuses. Please, let this change by Halloween. I am not taking her trick or treating in an old Disney nightgown, and no we are not wearing the chicken costume shopping after Halloween.