为什么美国签证预约系统注册不成功

第一次预约美国签证，可是注册不上，怎么办啊？给使馆打电话能注册吗？总是显示The system is temporarily unable to respond to your request. Please try again in a few moments.User could not be created. Please ensure First Name and Last Name are entered as they are in your passport.0 Y7 |8