is it possible use code validation in the group field? 

hi
in the group field i have two datetime field . one for start school and other for end of time in that school. i use cb code validation but it can not work when i add more row in that field group. am i correct way? is it possible validate some field in the group field ? i see in your demo and in you demo is also can not validate both time validation together. in fact i want comparison two field in each row of field group.
i use this in my code validation:
return ( strtotime('[cb_available_end_time]') > strtotime('[cb_available_start_time]')  );
i understand this topic maybe must under developer subs but i want understand it is a bug or it can not implement or i must more try?

I cannot help you with paid products without an active subscription, sorry.

This has been a recurring theme with your previous posts. It does not matter if it's a bug or not as we've no clue if your install is even up to date so it's possible your issue has been long fixed. Regardless if we did investigate, determine there was a bug, and fix it you wouldn't receive the fixed release as you don't have an active subscription.