Problems retrieving Hex-STRING in c++

Hi all!

Im new coding with net-snmp, so please be gentle...:)

I have some problem retrieving mac-addresses with net-snmp. I have som code that works exellent retrieving text-strings, but when i try to retrieve a mac address from a Mikrotik router (ex. .1.3.6.1.2.1.2.2.1.6.3) im getting nothing back.

Here is my code:

string SNMPController::snmpSendRequest(string _oid)
{
 count=1;
 result = "";
    anOID_len = MAX_OID_LEN;
    int status = 0;
     //Open the session
    SOCK_STARTUP;
    ss = snmp_open(&session);                     // establish the session
    if (!ss) {
        snmp_perror("ack");
 // MessageBox("Could not open session!");
        snmp_log(LOG_ERR, "something horrible happened!!!\n");
  result = "ERROR";
    }
    pdu = snmp_pdu_create(SNMP_MSG_GET);
 read_objid(_oid.c_str(), anOID,&anOID_len);
    snmp_add_null_var(pdu, anOID, anOID_len);
  
 // Send the Request out.
    status = snmp_synch_response(ss, pdu, &response);
   
 // Process the response.
    if (status == STAT_SUCCESS && response->errstat == SNMP_ERR_NOERROR)
 {
      
  // SUCCESS: Print the result variables 
  for(vars = response->variables; vars; vars = vars->next_variable)
   print_variable(vars->name, vars->name_length, vars);
  // manipuate the information ourselves
  for(vars = response->variables; vars; vars = vars->next_variable) 
  {
   if (vars->type == ASN_OCTET_STR)
   {
    char *sp = (char *)malloc(1 + vars->val_len);
    memcpy(sp, vars->val.string, vars->val_len);
    sp[vars->val_len] = '\0';
    
    //printf("value #%d is a string: %s\n", count++, sp);
    result = (string)sp;
    
    deletesp;
   }
   else
   {
    char buf[1024];
    snprint_variable(buf, sizeof(buf), vars->name, vars->name_length, vars);
    result = (string)buf;
    //printf("value #%d is NOT a string! Ack!\n", count++);
   }
  }
    } 
 else
 {
       //FAILURE: print what went wrong!
       
      if (status == STAT_SUCCESS)
   {
  fprintf(stderr, "Error in packet\nReason: %s\n",snmp_errstring(response->errstat));
  AfxMessageBox(snmp_errstring(response->errstat));
  result = "ERROR";
   }
      else
   {
        snmp_sess_perror("snmpget", ss);
  result = "ERROR";
   }
    }
 
      //Clean up:
       //1) free the response.
       //2) close the session.
     
    if (response)
      snmp_free_pdu(response);
    snmp_close(ss);
    SOCK_CLEANUP;
 returnresult;
}

Any help with solving this would be VERY apreciated!

best regards
Erik