Here is the ls result in Terminal.
You don't want filemac etc in the path name. I believe you could do without Volumes as well. "Filemac" expects a file. Not a directory.
Rick, You were part right.
I did have to specify filemac:. It worked by dropping the Volumes. I guess it assumes that it is mounted on the Volumes folder.
My current path is now, filemac:/Macintosh-HD2/FileMaker.databases/
The FileMaker help page states: