Hello Majdi,
I believe this might be a binding or DNS resolution issue. This behavior indicates the API couldn't be accessed using the hostname you provided, and responded instead from the IP address. If you are not running the site in IIS I suggest moving it into there and setting up bindings for both the hostname and IP address, then testing this once more. If you are already running in IIS I would check to make sure you have the hostname added as a binding.
Kyle Kerst
IT Coordinator
SmarterTools Inc.
www.smartertools.com