401 Unauthenticated?

[LetsCNow]

I have a sandbox key and secret and have them placed in the code but I am getting this:
What might I be missing?

Error calling SubmitPrimaryTransaction:
{
"clientRequestId":"df7daac4-9fc9-4804-9e46-56c2d9f50849",
"responseType":"Unauthenticated",
"error": {
"code": "401",
"message":"Unauthenticated"
}
}