[Plugin: Event Calendar 3 for PHP 5.3] RSS feed sorts on publish date instead of eventdate

Hello,

I am trying to get an RSS feed sorted ascending by event date.
I have come up with the following URL:

https://dirkzwagerieit.nl/category/evenement/feed/?ec3_after=today&order=asc

But as you can see it sorts on publish date instead of event date.
What should I add to get my feed sorted well?

Thanks in advance for any help.

https://www.ads-software.com/extend/plugins/event-calendar-3-for-php-53/