can not save spreadsheet from a windows service on windows server

[dragonemp]

I have a service app that create excel spreadsheet automatically. this worked
on xp and windows server 2003. but now i need it work on windows server 2008.
When the service run to this line
_workBook.SaveAs(excelPhysicalFilePath,Excel.XlFileFormat.xlWorkbookNormal,null,null,false,false,Excel.XlSaveAsAccessMode.xlExclusive,false,false,null,null,null) ;
it always returns error "System.Runtime.InteropServices.COMException
(0x800A03EC): Exception from HRESULT: 0x800A03EC"

however, I also has an windows form test app which runs exact same code, but
it works. So i wonder maybe the error is related to some new restriction
implemented for service/DCOM in windows server 2008, can somebody give me
some idea how to solve it?

 

[Alan Moseley]

Is it permissions? Your service will either be running under the Local
System account, or you will have specified it to use another account. If it
is running under Local System then try assigning another username to it (in
the Services applet in Administrative Tools).

Alternatively, is excelPhysicalFilePath pointing at a mapped drive? Mapped
drived do not exist from a service's perspective.

 

[dragonemp]

It's not permission, my service is run under local system and the folder has
been given full control to everyone......
I believe it has something to do with the way windows server 2008 handles
service/DCOM call, because that's the only difference between the test app
and service.
and excelPhysicalFilePath is pointing to local drive.