Sorry, Net Use is working on my AOS and thought you might have an issue with syntax. Error 59 is an unexpected network error which often is the result of a security negotiation error.
If you are trying to connect to a Linux samba share, try adding "ntlm auth = yes" in your smb.conf global section, which allows security negotiation to start with NTLMv1 (and above). If it's a Windows share, there's an older post on this forum describing the steps to modify Windows security.