[Plugin: WP Online Store Final Beta Version (osCommerce)] When plugin is activated: PHP errors and w

When I install this plugin, I get the following errors:

Warning: fopen(/var/www/www.domain.com/wp-content/plugins/wp-online-store/admin/includes/configure.php) [function.fopen]: failed to open stream: Permission denied in /var/www/www.domain.com/wp-content/plugins/wp-online-store/WP_online_store.php on line 151

Warning: fputs(): supplied argument is not a valid stream resource in /var/www/www.domain.com/wp-content/plugins/wp-online-store/WP_online_store.php on line 152

Warning: fclose(): supplied argument is not a valid stream resource in /var/www/www.domain.com/wp-content/plugins/wp-online-store/WP_online_store.php on line 153

Warning: fopen(/var/www/www.domain.com/wp-content/plugins/wp-online-store/includes/configure.php) [function.fopen]: failed to open stream: Permission denied in /var/www/www.domain.com/wp-content/plugins/wp-online-store/WP_online_store.php on line 157

Warning: fputs(): supplied argument is not a valid stream resource in /var/www/www.domain.com/wp-content/plugins/wp-online-store/WP_online_store.php on line 158

Warning: fclose(): supplied argument is not a valid stream resource in /var/www/www.domain.com/wp-content/plugins/wp-online-store/WP_online_store.php on line 159

Warning: chmod() [function.chmod]: No such file or directory in /var/www/www.domain.com/wp-content/plugins/wp-online-store/WP_online_store.php on line 161

Warning: include(configure.php) [function.include]: failed to open stream: No such file or directory in /var/www/www.domain.com/wp-content/plugins/wp-online-store/admin/includes/application_top.php on line 34

Warning: include() [function.include]: Failed opening ‘configure.php’ for inclusion (include_path=’.:/usr/share/php:/usr/share/pear’) in /var/www/www.domain.com/wp-content/plugins/wp-online-store/admin/includes/application_top.php on line 34

Warning: require(DIR_WS_FUNCTIONScompatibility.php) [function.require]: failed to open stream: No such file or directory in /var/www/www.domain.com/wp-content/plugins/wp-online-store/admin/includes/application_top.php on line 41

Fatal error: require() [function.require]: Failed opening required ‘DIR_WS_FUNCTIONScompatibility.php’ (include_path=’.:/usr/share/php:/usr/share/pear’) in /var/www/www.domain.com/wp-content/plugins/wp-online-store/admin/includes/application_top.php on line 41

And there is no menu shown up in the backend…

http://wordpress.org/extend/plugins/wp-online-store/