DS160网页说北京大使馆没有开放学生签证??

我本来是填表的时候选的是广州，但是今天一整天一直都只有北京在放位置，于是抢了个北京的位置。
结果在重新填DS160表的时候(选择了Beijing China)，填到purpose of trip to the us，选择了F,F1在保存时弹出:
You have indicated that you will be appying for the following visa class:. The location that you selected to process your visa is BEIJING CHINA. This location dose not process the visa class that you have selected. Please select an IV processing post below, or if the visa class that uou have selected is incorrect, click cancel and change your purpose of trip to the us

IV processing posts选项里国内只有广州……

不知道是出了什么问题？