Api schedule dayparting

I’m using API to set a schedule for my cms. When I set a fromDt and dayPartId:1 without assigning toDt, I receive an error:
“message”: “Can not have an end time earlier than your start time”,
and when I assign toDt, the dayPartId:1 doesn’t affect my schedule.

How can I just have toDt, and dayParting always?

If you’re using the “always” day part you shouldn’t need to provide date at all. Can you call the /daypart end point to make sure the always day part has the ID you’re expecting (its not always 1).