Vista - Unable to fax programmitically

Hi,

I am trying to send a fax from my application but am having no success. The program throws an exception when the fax is submitted. Unfortunately the exception text is "Operation failed" with no other error code information. Below is the relevant code in C#. Any assistance would be appreciated.

Note that I am running Vista Ultimate edition with service pack 1.

FAXCOMEXLib.FaxServer fs = new FAXCOMEXLib.FaxServer();
FAXCOMEXLib.FaxDocument fd = new FAXCOMEXLib.FaxDocument();
fs.Connect("");
//fd.Body = "This is the fax text.";
fd.Body = "C:\\Testfax.txt";
fd.DocumentName = "Test Fax";
fd.Priority = FAX_PRIORITY_TYPE_ENUM.fptHIGH;
fd.AttachFaxToReceipt = true;
fd.Recipients.Add("123-123-1234", "Test Recipient Name");
fd.CoverPageType = FAX_COVERPAGE_TYPE_ENUM.fcptNONE;
fd.Subject = "Test";
fd.Sender.City = "MyCity";
fd.Sender.Company = "ACME Computing";
fd.Sender.Country = "Canada";
fd.Sender.FaxNumber = "123-123-1234";
//This JobID[0] can be used to store the JobID of the fax job for later reference.
//string[] JobID = (string[])fd.ConnectedSubmit(fs);
fd.ConnectedSubmit(fs);