Vumark generation api usage with react

Hi i'm trying to generate an instance of a vumark via the web service I've already setup the database, I managed to make the request but I'm getting the 401 (Unauthorized) error code. Here is my code any help would be great. export const generateInstanceOfMarker = (vuMarkid) => {     const date = new Date().toUTCString();     var StringToSign = "POST" + "\n" + "B1E249BECDC69913C8BCCA597C2AF8DD" + "\n" + "application/json" + "\n" + date + "\n" + "https://vws.vuforia.com/targets/{target-id}/instances/" + vuMarkid;     var Signature = new HmacSha1('base64');     Signature.digest({server_secret_key}, StringToSign);     const Auth = 'VWS {server_access_key} : ' + Signature;     return dispatch => {         axios             .post(                 'https://vws.vuforia.com/targets/{target-id}/instances',                 {                     headers: {                         'Authorization': Auth,                         'accept': 'image/svg+xml'                     },                     body: {                         instance_id: vuMarkid                     }                 }             )             .then(response => {                 console.log(response);                 dispatch(onCreateInstanceEvent(response.data));             })             .catch(error => {                 console.log(error);             })     }; }; I create the md5 hash with this page : https://passwordsgenerator.net/md5-hash-generator/ and the text that i has was the body : body: {

                        instance_id: vuMarkid                     } Dont know which part of the authentification code is wrong. Thanks!