Turning script switches on and off via script commands + UMS

[Dorcot Bacon PhD]

I did some searching through the archives of posts, FAQs and Google, but all I'm looking for is a simple answer.

I'm using Fukuyama's caterpillar script and i read that it is possible to change the opacity (ie turn off trailing) by changing this line of code

TRANSPARENT_SWITCHES_INDEX = 20

to anything but 20.

Is this a plausible solution (turning on and off the trailing) for an event which opens the door before the main actor goes in, the actor moves forward, then closes the door behind him.

Without train actors, this works fine, but when I have people follow me, well, you know the rest.

Thanks!

Edit: Clearing the explanation up a little: door opens -> actor goes in -> actor opacity = 0 -> door closes (but that leaves my poor trailers facing a closed door before teleporting to a new map)

Edit 2: While I'm here, I might as well ask about ccoa's UMS and train actors.

In the comment section of the script it says two things about TAs: one being you can use the code \ta[1] to center it over train actor 1, and two is that you can use the code

$game_system.train_actor = 1

to do this, but I get the same error

Script 'UMS' line 1262: NoMethodError occurred.

undefined method `actors' for nil:NilClass

when I try to use them. Help!