'unknown error' on post iOS sdk

Hi, I'm just getting into the echonest sdk, so I apologize if this is a newbie question.

When do a post outside of the iOS sdk like this:

http://developer.echonest.com/api/v4/tasteprofile/list?api_key=API-KEY

I get good json data.

However when I do this in my xcode app:

[ENAPIRequest POSTWithEndpoint:@"tasteprofile/list" andParameters:nil andCompletionBlock:^
              (ENAPIRequest *request)
              {
                  if (request.completedSuccessfully)
                  { //DoSomething }
                  else
                  {
                      NSLog(@"Echonest errorMessage: %@", request.errorMessage);
                  }

request comes back unsuccessful.