Default Test Endpoint yields Bad Gateway error (using the suggested demo url indicated below):

curl -X POST --include ‘https://yarn.p.mashape.com/v1/vocabulate’
-H ‘X-Mashape-Key: e8MG5ArOrUmshjKGsWgxXvgC21KPp1TeR4rjsnKLX5Rx8tRfYi’
-H ‘Content-Type: application/x-www-form-urlencoded’
-H ‘Accept: application/json’
-d ‘fields=page,averages,leaderboards’
-d ‘url=http://www.bbc.co.uk/news/education-24433320’