Aerilius has you on the right track. Maybe this additional info will help: When a trusted web site, e.g. ‘http://www.houseofbread.org/’, is substituted for your link, the code works and produces the html body.
Your site is not trusted. Using the Chrome browser and just clicking on your link to ‘…/plans’, gives me this scary message:
Your connection is not private
Attackers might be trying to steal your information from testapi.sentiovr.com (for example, passwords, messages, or credit cards). …
This server could not prove that it is testapi.sentiovr.com; its security certificate is not trusted by your computer’'s operating system. This may be caused by a misconfiguration or an attacker intercepting your connection.