FTP error using a MAC

We are using a miniMAC [Mac OS X 10.4.11 (852167) Darwin 8.11.1] and
attempting to FTP to a Microsoft Windows 2003 (Web Edition) FTP Server
published via ISA 2000.

We can access the FTP server via a Windows PC using WS_FTP, windows explorer
or the command line FTP however when attempting to FTP from the miniMAC we
get errors;

Using OneButton FTP the transcript from the session was as follows;
220: Microsoft FTP Service

USER *******

331: Password required for *******.

PASS xxx

230: ******* FTP Server

User ******* logged in.

PWD

257: "/" is current directory.

PWD

257: "/" is current directory.

PWD

257: "/" is current directory.

CWD .

250: CWD command successful.

PASV

227: Entering Passive Mode (*,*,*,*,16,75)

LIST -a

426: Connection closed; transfer aborted.

LIST

150: Opening ASCII mode data connection for /bin/ls.

425: Can't open data connection.


Does anyone know what is going wrong here or how we can troubleshoot this
issue?

Regards
Kevin

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