"instead" only working in some situations

Hi! I am new to inform so this is probably a typical newbee question.
I am using Inform 7 and have found out that I can block actions by writing “instead”. However, it seems that I cannot use the “instead”-rule with “dropping object in something”, as I try to in the following example:

[code]the gym is a room. “You are in a big living room. In the middle of the room is a swimming pool.”.
the swimming pool is scenery in gym.
the branch is in gym.

instead of taking pool:
say “You cannot take a swimming pool.”

instead of dropping branch in pool:
say “you don’t want to loose the branch, so you decide not to.”.
[/code]
The code compiles fine, but when I type “drop branch in pool” I simply get the default message: “That can’t contain things.” I have tried making the pool a container instead but that doesn’t help.
So can anyone explain to me why “instead” works for “taking pool” but not for “dropping branch in pool” and is there a workaround so that I can achieve what I am trying to do? (I want to be able to throw selected objects only in the pool.)
Thanks

Inform’s picky about how you specify action names. It’s reading “dropping the branch in the pool” as “(dropping (the branch)) (in the pool)”: that is, dropping the branch when the location is the pool. The action for “put X in Y” or “drop X in Y” is called “inserting it into”.

By the way, the player won’t be able to put anything into the pool unless you make it a container.

Thanks you two, exactly what I needed.

Also, you defined the pool as a scenery item, which is why ‘Instead of taking pool’ did work.

Well, it’s true that the Check rules would bar taking the scenery pool if they were ever consulted. (“That’s hardly portable.”) But Denk’s “Instead of taking the pool” kills the action before it gets to the Check stage.