What's wrong with using 内に in this sentence?


My textbook claims that this is an incorrect usage of uchi ni:

> 彼が会社に行っている内に、贈り物が届きました  
>  While he is commuting to the office, a present arrived.

Why is this wrong? It looks fine to me.




Not 100% positive on this, but I would say 行っている **間** に. `内に` usually
indicates "while it is in state X", but implying that state X will eventually
change to state Y, and the action is undesirable/impossible in state Y. The
example I usually try to remember is

> スープが温かいうちに飲んでください → Eat (drink) your soup while it's still warm.

because once it cools down, it won't be as delicious; desirable to eat; etc.

So I think `内に` doesn't fit because the present could have still been
delivered each after his state changed from "going to the office" to another
state ("being at the office", "going to lunch", etc.)

