再次 and 再: are they different? Here is the context: 我于是去了这家餐厅，点了一盘蘑菇菜心，果然好吃。我对服务员说: 我再次要一盘。

The sentence "我再次要一盘" is wrong. But "我再要一盘" is correct. Can anyone explain why?
The answer by  Camila Ting Chen is close. We don't use 再次 in an present active sentence. We use 再次 with some perfectness or passiveness. Such passiveness is not necessarily related to the conjunctive 被 however. A simple rule is when we can say 再 alone, say it alone.

我再次来到这家餐厅。

我时隔数年再次遇到一位朋友。

这盘菜再次被我吃掉了。 while this sentence is not logical at a first glace, it sound good in this specific situation.