ODK collect cannot find the app engine server


I am trying to send a form from my ODK collect on my phone to the app engine server. The server address is https://nord-ubangi---girl-rising.appengine.com. This is what I put in ODK collect. I have correctly entered all the usernames and passwords on app engine and ODK collect.

When I send the form I get the following message:

Error: Not found (404) at server https://nord-ubangi---girl-rising.appengine.com/submissions and it gives the IMEI code.

Can anyone help me get this working?

Many thanks!