When asking for help, it helps to have done a little extra work first:

1. Look in Options menu of scripts editor, and make sure that "identifier warning" is checked, so you get an error in status window instead of using $null
2. Please describe what the script should do, and give an example of what we should do to trigger the problem. i.e. is it doing something it should not do, or is not doing something it should do?
3. If there are not any error messages, please say that.
4. Please include enough of the script. In this example, your example calls the "canales" alias but you did not include it. Either your status window is filled with warnings that canales is an unknown command, or you did not include it.
5. If you can put your script inside the "code" and "/code" block, that makes it easier to read it. You can find it in the "#" icon above where you type your post.

Assuming that you had a typo mistake, I changed your raw event to call canales1 instead, but that still does not work, because it assumes there is a dialog named new_table but you did not include anything for this at all. Assuming this is another typo, I changed "new_table" to the name of your dialog "canales" and everything seems to be ok. However, I doubt that this is intended, because repeating the /list command would keep adding extra rows to the dialog without removing the existing list.