Verify that you have a Microsoft Translator API subscription in the Azure portal at https://portal.azure.com.
If you need help creating a subscription, follow the steps outlined in the Try Microsoft Translator webpage.
Microsoft Translator generally will let your first couple of requests pass before it has verified the subscription account status. The error response will indicate the problem. Please log the API response so you can see the reason.
- Edited on January 25, 2017