You need to provide much more detail:
What is the FTP server running?
What port?
FTP or sFTP?
Using IP address or Hostname?
How have you formatted the path on the webui of the printer?
Are you adding leading and trailing slashes ala /Folder one/Folder2/ or no?
Are you using a login or attempting to do this with Anonymous?
Is the Gateway and Time and Subnet correct on the device? If using Hostname is DNS setup properly for the internal network?