Renaming error (123)

It seems I'm having a problem renaming both files and folders in Directory Opus. Every time I try and rename a file using a "space", for example, renaming a folder "Party Pics", it won't allow me to do it. I get the error:

"An error occurred renaming "PartyPics": The filename, directory name , or volume label syntax is incorrect . (123 )"

What could be going on here?

Is it on a network drive? If so, which OS is at the other end?

Or does it have a very long path name leading up to that folder?