Content Delivery API - Filter by date

Hi,

I've installed the latest version of Episerver Content Delivery API 2.6.1. I need to call the api to get all events after a specific date and it seems that I can't filter the events by date.

I've tried the example provided by Episerver here: https://world.episerver.com/documentation/developer-guides/content-delivery-api/content-search-api/#Filtering

but when I test it in my solution

Get /api/episerver/v2.0/search/content/?filter=startPublish ge 2019-09-11T09:47:19Z

and getting this error message:

{"error": {"code": "InvalidFilterClause","message": "Unable to parse provided filter clause"
    }
}

Is anyone able to filter the content by date?