“因为” 是个连词或介词概念；“原因” 是个名词概念。

“因为” 的表达：because, as, since, for, because of, owing to, due to, on account of， thanks to...

“原因” 的表达：cause, reason, excuse, account

英语常用的两个表达式：

This is because ... （提供原因或理由）

That is why... （说明结果）

例如：

This is because he is ill.

That is why he hasn't come.
此“因果关系”， 你不能用错了格式。你把 becuase 和 why 换过来，试试。