Wordpress Dashboard stops working after installing PhotoGallery

Hi :)

After installing Photo Gallery Plugin my wordpress dashboard stops working with the following error:

Warning: mkdir(): No such file or directory in /homepages/46/d86407055/htdocs/clickandbuilds/xxx/wp-content/plugins/photo-gallery/framework/BWGOptions.php on line 365

Warning: Cannot modify header information - headers already sent by (output started at /homepages/46/d86407055/htdocs/clickandbuilds/xxx/wp-content/plugins/photo-gallery/framework/BWGOptions.php:365) in /homepages/46/d86407055/htdocs/clickandbuilds/xxx/wp-includes/pluggable.php on line 1296

Warning: Cannot modify header information - headers already sent by (output started at /homepages/46/d86407055/htdocs/clickandbuilds/xxx/wp-content/plugins/photo-gallery/framework/BWGOptions.php:365) in /homepages/46/d86407055/htdocs/clickandbuilds/xxx/wp-includes/pluggable.php on line 1299

If I remove the plugin via FTP the page works again without problems. After reinstalling this error appears again. All my other plugins are working.

The website ifself (http://s522462560.online.de/projekte/) works, even the gallery works but there is also this error on the top of the site.

Can you please help me? Any idea what's going wrong?

Thanks!

Bernhard