Hello -- I'm in need of some expert help with a Trailhead module. I'm working on the module "Automate Order-to-Cash Process Using MuleSoft Flow Designer", and when I test the final result, I'm getting the following message from the Twilio Connector:

HTTP POST on resource 'https://api.twilio.com:443/2010-04-01/Accounts/ACxxxxxx/Messages.json' failed: bad request (400)

(Note that ACxxxxxx is my Account SID for Twilio, masked for display purposes)

I'm very new to Mulesoft, so it's not beyond the possibility that I'm doing something wrong. But I'm having difficulty troubleshooting. I've followed the Trailhead units exactly as instructed (twice, in fact) with the same results each time. I'm wondering if the Trailhead module needs to be updated due to updates made to Mulesoft and/or Twilio?

Have others experienced this? Any help anyone is willing to share, I'd be most appreciative.

Thanks!