If you can access your ftp server via any ftp client like Filezilla then you will be able to list directories via ColdFusion as well. Share the stack trace as well.
Sample Code
<cfftp
port="21"
action = "open"
username = "username"
connection = "ftp"
password = "password"
server = "abc.xyz.com"
stopOnError = "Yes">
<!--- Confirmation of Open --->
<cfoutput> Connection Open :#cfftp.succeeded# </cfoutput>
<p>List the files in a directory:
<cfftp
action = "LISTDIR"
stopOnError = "Yes"
name = "ListFiles"
directory = "/"
connection = "ftp">
<cfdump var="#ListFiles#">
<cfftp
action="close"
connection="ftp"
stopOnError = "Yes">
<!--- Confirmation of Close --->
<cfoutput> Connection Closed :#cfftp.succeeded# </cfoutput>
HTH
Thanks
VJ