Purchased the Gravity Forms integration with DataTables add-on

Documentation mentions activating the add-on, but no obvious place to enter the purchase code in the WP dashboard

Still, when creating a new data table I do see the option to create one with Gravity Forms as a data source.

I choose the simplest form I have, it retrieves the field list correctly, I "select all"

Then when pressing Apply I get a red error box on the upper right of the browser window, and the page hangs.   Come on!  No way to diagnose the problem?

This really sucks -- I read the overview documentation and examples, tried an extremely straightforward example, and not only didn't it work, there is no way to figure out what to do next.

Version 2.1 of wpDataTables.

Also, I just noticed this in the error log -- the fatal at the end is probably relevant ---

[17-Dec-2017 23:43:15 UTC] PHP Notice:  Trying to get property of non-object in /home1/musical9/public_html/online-registration/wp-content/plugins/wpdatatables/templates/admin/table-settings/add_column_modal.inc.php on line 72
[17-Dec-2017 23:43:15 UTC] PHP Warning:  Invalid argument supplied for foreach() in /home1/musical9/public_html/online-registration/wp-content/plugins/wpdatatables/templates/admin/table-settings/add_column_modal.inc.php on line 72
[17-Dec-2017 23:43:15 UTC] PHP Notice:  Undefined variable: tableData in /home1/musical9/public_html/online-registration/wp-content/plugins/wpdatatables/templates/admin/table-settings/remove_column_modal.inc.php on line 40
[17-Dec-2017 23:43:15 UTC] PHP Notice:  Trying to get property of non-object in /home1/musical9/public_html/online-registration/wp-content/plugins/wpdatatables/templates/admin/table-settings/remove_column_modal.inc.php on line 40
[17-Dec-2017 23:43:15 UTC] PHP Warning:  Invalid argument supplied for foreach() in /home1/musical9/public_html/online-registration/wp-content/plugins/wpdatatables/templates/admin/table-settings/remove_column_modal.inc.php on line 40
[17-Dec-2017 23:43:44 UTC] PHP Fatal error:  Call to undefined function WDTGravityIntegration\array_column() in /home1/musical9/public_html/online-registration/wp-content/plugins/wdt-gravity-integration/wdt-gravity-integration.php on line 321

Thanks,

Steve

I disabled mod_security for the subdomain, but the problem still shows up.  Very odd that if it's a security issue, why would it appear only for this particular code path for this particular plugin?  Seems like the same code would be loaded on every page serve.

Also, doesn't this concern you:  that fatal from the error log appears consistently for this code path.

[19-Dec-2017 14:50:33 UTC] PHP Fatal error:  Call to undefined function WDTGravityIntegration\array_column() in /home1/musical9/public\

_html/online-registration/wp-content/plugins/wdt-gravity-integration/wdt-gravity-integration.php on line 321

I see that the PHP function array_column is defined as of PHP version 5.5 but the site is running on PHP version 5.4.43.  Seems like that might be relevant to the problem?

I updated PHP to 5.6.  It works now.  Man, I'm no expert on software engineering as it applies to Wordpress and plugins, but as a software engineering practice, releasing libraries that are not compatible with a common production version of PHP (I say that because it's the default you get from Bluehost) *and* don't have checks in the code to detect the incompatibility seems like really bad practice.