fatal error using version 3

Hallo Team, i see this error using your addon with Ultimate membership pro.
could you help me?

Fatal error: Uncaught Error: Class ‘VC_MEGA’ not found in /home/stockpic/rendimentofondi.it/wp-content/plugins/mega-addons-for-visual-composer/index.php:30 Stack trace: #0 /home/stockpic/rendimentofondi.it/wp-settings.php(342): include_once() #1 /home/stockpic/rendimentofondi.it/wp-config.php(91): require_once(‘/home/stockpic/…’) #2 /home/stockpic/rendimentofondi.it/wp-load.php(37): require_once(‘/home/stockpic/…’) #3 /home/stockpic/rendimentofondi.it/wp-content/plugins/indeed-membership-pro/public/paypal_payment.php(2): require(‘/home/stockpic/…’) #4 {main} thrown in /home/stockpic/rendimentofondi.it/wp-content/plugins/mega-addons-for-visual-composer/index.php on line 30