Sending Fax From Windows Service

I am trying to send the fax from my windows service which is written in vb.net. I am facing problem with windows 7 and windows 2008 Server. It works fine with Windows XP. Fax is not getting visible in fax console's outbox. I saw three files in "C:ProgramDataMicrosoftWindows NTMSFaxQueue" for every sent fax but this is not visible in fax queue. I also observed that, when I am trying to send the fax from windows application then it works but anyhow it is getting failed when I am trying to send that from windows service.

I have following code :
Dim oFaxSvrType As Type = Type.GetTypeFromProgID("FaxcomEx.FaxServer")
Dim oFaxSvr As Object = Activator.CreateInstance(oFaxSvrType)
Dim oFaxDocType As Type = Type.GetTypeFromProgID("FaxcomEx.FaxDocument")
Dim sFaxServerName As String
[Code] .....

I observed that in task manager, rundll32.exe is getting started when I tried to run this code from windows application but this rundll32.exe is not getting started when I am trying to run this code from windows service. I am not getting any exception after executing this code but not able to see the fax on outbox. I ensured that allow service to interact with desktop in service console is checked for fax service and my own windows service.