FACETIME DOESNT WORK!!!!

im trying 2 use facetime to call my friend and it just says..connectingand she know i want to call her. she has WIFI and also the call comes in bt when i accept it takes forever to connect. then, it says that she is nt available for F.T whyy?? i mean i tried to call her on another ipod and it works!! i need help. and i just purchased this new ipod.