Fatal error – help

Hi

I am trying to active the plug in “all-in-one Event calendar by Timely” and I am getting the following message:

Fatal error: Cannot redeclare class vevent in C:\xampp\htdocs\GRACEtestsite\wp-content\plugins\all-in-one-event-calendar\lib\iCalcreator-2.16\iCalcreator.class.php on line 6663

Any ideas?

Thanks