Hello, I have been stuck on a callout I'm trying to make. When I did it from POSTMAN it worked successfully (i received a 200 response code), however it is not going through from Salesforce. Can anybody tell me if I'm either missing any steps or doing Named Credentials wrong? Please keep in mind that for this callout, I do not need user name or password, rather the external system vallidates the system based on certain information from the body of the callout itself.) 

Here's my code, named credentials, and static resource:

Code:

    public final Lead referral;
    public String requestLabel;
    public String result {get;set;}
    public List<Object> seekData {get;set;}
    public string reqbody;
 StaticResource r =[Select Id,Body from StaticResource where Name='Seek_Callout_Body' limit 1];
      reqBody=r.body.toString();
       HttpRequest req = new HttpRequest();
         //  req.setHeader('Content-Length','0');
                req.setHeader('Content-Type','text/xml');
                req.setMethod('POST');
                req.setBody(reqBody);
                req.setEndpoint('callout:Seek');
                req.setCompressed(true);
    system.debug('FULL REQUEST: ' + req);

         Http http = new Http();
           HttpResponse response = http.send(req);
        // Parse the JSON response
        if (response.getStatusCode() != 201) {
            System.debug('The status code returned was not expected: ' +
                response.getStatusCode() + ' ' + response.getStatus());
        } else {
            System.debug(response.getBody());
        }


Static resource is .txt file of this: