Requesting access token in (c#)

HI, I've been trying to to get the oath process working but I’ve been struggling with requesting the access token. I have triple checked that all the details are correct (client_id and secret) and that the status is indeed Active yet I'm getting an invalid_client error message back when attempting to request an access token. Here is the full response I get when making the request using the Postman application:
Cache-Control →no-store
Connection →keep-alive
Content-Length →26
Content-Type →application/json;charset=UTF-8
Date →Sat, 02 Sep 2017 12:24:08 GMT
Pragma →no-cache
Server →Mashery Proxy
WWW-Authenticate →Basic realm=""
X-Error-Detail-Header →Account Inactive
X-Mashery-Error-Code →ERR_403_DEVELOPER_INACTIVE
X-Mashery-Responder →

When attempting to do the same but in code the application just hangs forever without ever receiving a response back. Any help would be greatly appreciated; I have already gone through all relevant forum posts and gone through the documentation but non of it has solved my issue. Thanks in advance.

Sorry for the delay it getting back to you. What does your post body look like?