I'm creating a campaign through the OpenX API, and so far so good *but* i need to set an end date to the campaign, via the endDate parameter; the thing is: i don't know what i should bind to the parameter on the API call. I tried using this: `$date = date("Y-m-d H:i:s",strtotime(date("Y-m-d H:i:s") . $date_threshold));` where `$date_threshold` is something like `"+1 month"`, but the endDate won't appear on the OpenX panel.

What kind of data do i need to bind to that parameter so it's correctly inserted on the OpenX database? 
Thank you in advance.