[Zope] File url in a network

Hello, I need some help. I don'n know how to specify a file url in a network. For uploading and creating an object (within the Product External File) I need <dtml-call "uploadCreate(target_filepath=target,upload_file=fileurl)" > with the file_url as upload_file. I get the error [Errno 2] No such file or directory: \\192.168.1.172\C:\FH-Unterlagen\Vorlesungen\MT\KFZ-MT\Folien\Temp\Titelblat t.pdf when I use this function with the fileurl='\\192.168.1.172\C:\FH-Unterlagen\Vorlesungen\MT\KFZ-MT\Folien\Temp\ Titelblatt.pdf'. How can I specify the file in the network? Thank you for an advice Fritz Troester