如何使用Delphi中的DropBox REST API复制文件

I do not seem to manage the file copy operating using the dropbox api. I can successfully authorize my client, download and upload files. The copy operation needs POST method to be used and I think this is where I produce wrong request. I am defining the POST Method for OAuth Authentication and use Indy TIdHTTP to Post the request, but I always receive the error code 403 - Permission denied.I do not seem to manage the file copy operating