windows service
windows, windows-services
Solution
Here are some experiences I had while creating the same service as you did (reading and saving PDF on a network drive). I had 2 drives: The first without the need of authentication and the second where you had to authenticate.
Common faults with mapped network drives
UNC Path vs Drive Letter: Drive letter's don't work, you have to specify your path using the UNC notation. (e.g. \\10.17.194.1\RemoteDir\)
Authentication: If the network drive needs you to authenticate, the only way I found was to create the authentication user on the machine running the service. If you need to authenticate as "RemoteUser" with "RemotePassword" to access the network drive, you should create a RemoteUser/RemotePassword account on the server and let the service run as this user.
If you don't have the rights to access the directory you'll be getting a exception telling you it could not find the directory/file or rather that it does not exist.
Service can't establish connection by itself: Also, it is mandatory to access the network drive at least once manually from the explorer so you can browse it. My service was unable to establish a connection to the network drive by itself, it had to be established in the explorer before.
I hope any of this points help you.
Problem
I developed a windows service to write PDF file in a directory. The service has no problem writing files to local drives. But when it tries to write to network mapped drives, it fails and writes the file in the application directory.