[Cloner] Cloning of sub-websites

Hi folks, I am currently trying out WPMU.
This time I try to clone my sub-website "hasenfuss.almiro.de". Hoever, I only get the same error message:
"Notice: Undefined variable: additional_tables in /kunden/460122_31157/almiro_de/test/wordpress/wp-content/plugins/cloner/admin/cloner-admin-clone-site.php on line 429

Warning: Cannot modify header information - headers already sent by (output started at /kunden/460122_31157/almiro_de/test/wordpress/wp-content/plugins/cloner/admin/cloner-admin-clone-site.php:429) in /kunden/460122_31157/almiro_de/test/wordpress/wp-includes/pluggable.php on line 1223"

Can you help me? What is it that I do wrong?
I allowed support access for the site.