Rest Design API Request to create transaction Container

Using the NL Design API documentation. I am checking to see if I can able to trigger Http request to create a transaction Element in NL. I was able to Add UserPath but when i am trying to add transaction I am getting this error response saying "NL-DESIGN-CANNOT-ADD-ELEMENT(Element with uid not found)"
I am 100% sure i am giving the userid of its parent but still no luck. Can anyone help me with this? Thanks