Troubleshooting web hooks

I have setup some web hooks in my adobe sign profile to notify me when any action occurs.  My api url is accepted by adobe sign and I can test it successfully using fiddler but adobe sign is not triggering my api.

My api url is just a test at the moment, it simply sends me an email containing the json that was sent in the request.

How can I troubleshoot adobe sign and find out why my api isn't being called?