unix2dos not recogonizing outfile

I typed unix2dos /path/to/filename_unix.txt /path/to/filename_dos.txt in the CentOS 7 terminal, but I got the following in response:

unix2dos: converting file /path/to/filename_unix.txt to DOS format ...
unix2dos: /path/to/filename_dos.txt: No such file or directory
unix2dos: Skipping /path/to/filename_dos.txt, not a regular file.

What am I doing wrong?