lol, this tool is so old!
If you cannot enter the initial "[", then I do not know why because it actually works here. It is very strange...
If you look at the documentation provided, you will notice the function takes 2 arguments, therefore you must enter a number followed by a comma, followed by the direction argument. The program forces you to write with proper syntax. Perhaps there is a bug in the program that is preventing you from typing even valid syntax for some reason. Are you using a normal US English keyboard?
Maybe I will revisit this program one day and build an even better version.
Out of curiosity, what are you using this for?
Take care