undefined variable

I am getting an error warning which is displayed on our site:

Warning: Undefined variable $is_b2b_user in /customers/9/f/d/phoenixmusic.nl/httpd.www/wp-content/plugins/codecanyon-ySeZGUjo-b2bking-the-ultimate-woocommerce-b2b-plugin/public/class-b2bking-public.php on line 651

Please see attachment screen shot.

I also include the b2bking problem solving file which I downloaded from the Tools tab.

Could you please help? I don't know where to begin to look.

Thanks

Waldo Fenker

http://www.musicgifts.nl

Hello Stefan,

Thank you! That seemed to solve it. I deleted the old installation of the plugin and everything works fine now.

I appreciate the good support you give, after researching your plugin on line it was the major reason I chose for your company. I am so pleased that you live up to your good reputation. 

Thanks again.

Waldo