This means it can't create the mount path directory. It should be in /
Volumes/.
In finder, go to /Volumes/ (using apple-shift-g) and check for a
folder matching the volume name or server name.
If it exists, delete it. It should mount now. If not, also try
changing the "Mount Path" under the advanced tab.
Using something like "/Volumes/myHost" (without the quotes).
~ M.