On Windows it would work if you could specify the UNC path to the share. The best way to find out how FM wants to path to be is by trying to set that path manually in an export or import script.
Windows is kinda forgiving that in that respect because it does not require the share to be "mounted"
On OSX you would have to mount the share first and then figure out what the path would be by trying to use that share as an export destination or import source.
In both scenarios it will show you the syntax to use.
Is this script being run manually (from a client) or from a scheduled script?
Manually from a client computer (Usually a Windows)
At least on OS X there seems to be a problem with the save as pdf (search this forum). It works a few times, but then you get that kind of error message as written above. That might not be the reason why this script doesn't work, but I just wanted to put the spotlight on this if smac11shl is unable to find a solution.
I claim this has NOT to do with the file path. We have had the same problem. It has been difficult to prove this bug, as it seems to work different on different computers.
There is another known bug for which there is a solution. I believe most people here already did this, which is why they fail to get this save-as-pdf-bug, but that's my theory.
Anyway, after deleting the Adobe PDF plug-ins under Library -> Internet support, this bug DISAPPEARS for all my team members.