Error with a script.

[choboku]

First of all, sorry about my bad english. I'm spanish speaker.

I downloaded the Slipknot message system, which one you can find here in this forum: http://rmrk.net/index.php?topic=1767.0
It works perfect in the demo, but when I copy the scripts to my game, the message boxes get empty. I found a solution for that:
creating a new script above the "message system" script, with the label "font" and write inside it this line:

Font.default_name = "Tahoma"

Now the text appear, but it is Arial size 25. And I can't change the font whatever I do. ¿What am I doing wrong?