Unable to upload Image to server with MultipartFormFileSection , WWWForm and Upload Handler

I have tried every possible solution for uploading image to server using unity 5.6.2 , but still there is no success. I used legacy and latest methods as well .The server responds with response code 204. But when I use postman to check , it works fine and file is uploaded. Content-Type doesn't matter either use it or not. Here is my script. Thanx

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using System.IO;
 using UnityEngine.Networking;
 using System;
 public class SendData : MonoBehaviour {
 
     public void ButtonPressed()
     {
         StartCoroutine (sendImage ());
     }
 
     IEnumerator sendImage()
     {
         byte[] img = File.ReadAllBytes(Application.dataPath + "/scree.png");
         Debug.Log ("File Length " + img.Length);
 
         List<IMultipartFormSection> requestData = new List<IMultipartFormSection>();
         requestData.Add( new MultipartFormFileSection("file" , img , "scree.png" , "image/png"));
 
         UnityWebRequest request = UnityWebRequest.Post("http://mysite.com/uploadfile" , requestData);
         request.SetRequestHeader("Content-Type", "multipart/form-data");
         request.SetRequestHeader("EventID","1");
         request.SetRequestHeader("FileName","scree.png");
         request.chunkedTransfer = false;
         yield return request.Send();
 
         print("request completed with code: " + request.responseCode);
 
         if(request.error != null) 
         {
             print("Error: " + request.error);
         }
         else 
         {
             print("Request Response: " + request.downloadHandler.text);
         }
     }
 }