Downloading PDF using Google Data API SDK for .NET v1.8

I'm trying to download PDF file from Google Docs using the .NET libraries. I'm able to download every oth开发者_开发技巧er file type but PDFs. Is downloading PDF supported using the .NET libraries?

I've tried the follow C# code:

Stream docStream = request.Download(doc, null);

and

Stream docStream = request.Dowload(doc,  Document.DownloadType.pdf);

and

String docUrl = doc.DocumentEntry.Content.Src.ToString();
Uri docUri= new Uri(docUrl);
Stream docStream= request.Service.Query(docUri);

Each attempt returns "Execution of request failed" exception.

Today it started working as expected using the following line to download a pdf:

Stream docStream = request.Download(doc, null);