Call to undefined method G2\L\Extension::valid()

I couldn't find this topic in forum. Just installed Chronoforms 6 and creating basic form. When trying to preview I get this error message. Please advise. I have latest Joomla v 3.7.4 and PHP Version 7.1.3

I've added debug report

Thanks

Hi amheng5,

Do you have the latest v6 update ? please make sure you install Chronoforms AFTER connectivity or any other ChronoEngine extensions.

Best regards,
Max