Add new document using API in java

I'm using java client to upload new document. I'm using following code.

             MultipartEntity entity = new MultipartEntity();
           entity.addPart("authtoken", new StringBody(authToken));
            entity.addPart("projId", new StringBody(projectId));
            entity.addPart("docname", new StringBody(docName));
            entity.addPart("folderid", new StringBody(folderId));
            entity.addPart("tags", new StringBody(tag));

            ByteArrayBody bab = new ByteArrayBody(file.getBytes(), file.getOriginalFilename());
            entity.addPart("uploaddoc", bab);
            post.setEntity(entity);
            log.info("executing request " + post.getRequestLine());
            log.info("Params: "+entity.getContentLength()+" "+entity.getContentType());
             HttpResponse response = client.execute(post);

I'm getting error response like 'Invalid Ticket'. Can anyone help me on this?