To get Tomato uploads coming through to Nightscout, ensure that "Visualize therapy: yes" is enabled on the Welcome page.
https://www.t1pal.com/account/sites/my
This should allow Nightscout to receive the information from Tomato app.
Secondly, when Tomato asks for the Nightscout URL, use the Uploader Url and API Secret from the Uploader page.
Here's a video that may help:
You can learn more about Tomato here: http://tomato.cool/