Error when Uploading config from Cisco WLC 2100 to TFTP

So I am using my Cisco WLC 2100 to save my config file to a TFTP server. I have no problems connecting to the server, but I keep getting an error when it tried to create the file. I am using Tftpd32. Here is the info from the log viewer.

Connection received from 10.0.0.1 on port 7800
Write request for file . Mode octet
File : error 123 in system call CreateFile The filename, directory name, or volume lable syntax is incorrect.

Any ideas? Thanks.