dbxClient getFile failing with absolute output file path???

I'm using dropbox PHP SDK

I'm trying to download all newly added files using /delta API.

So, when I use dbxClient getFile method to download the newly added file, it successfully downloads the file only when I give the outstream as relative path.

The same getFile downloads a 0 bytes file when I give absolute path as outstream.

$download_file_path = $lsPath; --> This works

$download_file_path = '/opt/sample/dropbox_ingest' . $lsPath; --> This fails

$fd = fopen($download_file_path, "wb");
$dbxClient->getFile($lsPath,$fd,null);

Please let me know if i'm doing something wrong here!!

 

Thanks,

Srinivas