german shepherd pup will not eat

Question
i have a 9 week old female German shepherd have her a week now she will only eat once a day and is after losing weight i have a 6 year old male as well i feed the pup away from him i did not have this problem with him what should i do

PS: i had the pup at vet she told me to keep trying to get the pup to eat and keep an eye on the pup weight

Answer
Are you continuing what the breeder was feeding?  Sometimes they will eat the familiar food better.  
She should be adjusting to her new home, but be sure to give her plenty of attention.  It is quite normal for them to keep themselves very skinny, but shouldn't lose weight.