Connects to remote server but can't read remote directory

vEr 4.3.5 (build 1463)
Windows 7
ftp SSL explicit
new installation on new machine (have been using 4.3.3 build 1340 on previous machine - windows 7 with exact same settings)

Message indicates successful connection but error says can't read directory ('/')

"Connnected"
"Starting Session.."
"Reading Remote Directory.."
"Retrieving Directory Listing..."

Error Message:
Timeout detected.
Could not retrieve directory listing
Opening ASCII mode data connection.
Error listing directory '/'.

I am able to connect to the server using my other machine with exactly the same settings.

I went back in and manually forced it into passive mode (i.e. unchecked and then rechecked the Passive tick box)-

It works now!!