HTTP Header issue


My question is in regards to the HTTP Header. I am sending a XML header, but a JSON Body. I am trying to embed a basic auth into it yet I am having difficulties. I am sending below as my header, but the authorization part does not work. Anyone see anything wrong? I X’ed out my encrypted username and password.

<HttpHeaders><Key>Content-Type</Key><Value>application/json</Value></HttpHeaders><HttpHeaders><Key>Accept</Key><Value>application/json</Value></HttpHeaders><HttpHeaders><Key>Authorization</Key><Value>Basic XXXXXXXXXXXXX=</Value></HttpHeaders><HttpHeaders><Key>Method</Key><Value>Post</Value></HttpHeaders>