Hi Anke,
I just tested your code, and indeed, there is an issue: it is a matter of spaces insides the parentheses of importClass. It is an error on my side, so the engine has absolutely no problem running the code, but I fail at interpreting it correctly.
I'm going to address this bug, but if you want to stop having it before I upload a new version, simply remove those spaces will do it. Thank you for the report!
By the way, in the script editor, you can always use Edit > Format if you want to format your code automatically.
Cheers,
Thomas