Hello,
I'm not really sure what version you are using, but issue like that was solved in rc6 release (we're at 1.0.0 atm). Also - for both rc5 and rc4, your line mismatch with what is in the original package, so I presume that's slightly modified version?
Anyway, solution is quite simple, open that ***/modules/CRM/Calendar/Calendar_0.php and look for occurances of
Base_RegionalSettings:: ...
and replace with
Base_RegionalSettingsCommon:: ...
- should get things done.
I'd also recommend you, to try to upgrade your epesi installation sometime soon (after the presentation, I guess) - we have included many bug fixes and some minor new features, it's definitely worth to keep it up-to-date.
If it's not really a solution for you, please next time specify the version you are working on and if the file in which there's an error was modified by you, please attach it to the post.
Good luck,
Arek
