Teaching a child to zip a Jacket.

My DD is 8yrs old and still cannot zip a jacket up despite learning for a few months, I have been teaching a few times a day but she is struggling to pick it up, she keeps trying for about 20mins and then just gives up and runs of crying because she thinks she's useless plus she thinks she is the only 8yr old that can't zip a jacket, so, any advice on if there is a magic formula for speeding up process, or how I can help her stop giving up so easily?

just type how to zip a jacket in google, there will be a result of baby center, it may help you