I just installed DTRegister 2.7.16 on my Joomla 1.5.26 system, and everything went well until I try to add my first event into the component. The error I got was (in FireFox):
In Chrome, I got a more informative message:
Uncaught TypeError: Cannot read property 'DEF_DATE_FORMAT' of undefined calendar.js:14
Calendar calendar.js:14
DTshowCalendar validate.js:1194
onclick index2.php:1133
It looks like the locale was not declared properly for some reason.
The action is - Admin side, add event, click on [...] on event date to pick a date.
FireFox 12 and Chrome on OS X Lion
Joomla 1.5.26, CentOS 5, PHP 5.3.5
DTRegister 2.7.16 (just licensed Apr 27 and downloaded)
This is not a bug, but would be due to something else in your admin breaking the loading of scripts needed for DT Register. In most cases, this is due to using a poor or outdated text editor. Editors like FCK and CK are known to cause problems are normally found when there are problems like this. Using the default editor or JCE (the best option available), you wouldn't have this type of problem.
With an updated editor or quality, if you still have this type of problem, log a ticket.