ftp bounce attack

[Macs01]

I want to connect to my ftp-server. If I use a proxy-server I get the following error. I use total commander or WS-FTP Pro and I get a blank directory. Without a Proxy I have no problems to connect. It was possible to connect with Plesk 8.2.1.
I only have this problem with Plesk 9.5.2 + qmail

Connect to: (21.06.2010 16:36:44)
hostname=www.mydomain.com
username=ftpuser
startdir=/httpdocs
Firewall=proxy.server.local:21
proxy.server.local=10.10.10.10
220 FTP-Relay OK. Login with [email protected] use Passive Mode (passiv)!
USER [email protected]
331-
220 ProFTPD 1.3.2e Server (ProFTPD) [192.168.1.100]
331 Password required for ftpuser
PASS ***********
230 User ftpuser logged in
SYST
215 UNIX Type: L8
FEAT
500 Command not allowed by RFC959
CLNT Total Commander (UTF-8)
500 Command not allowed by RFC959
OPTS UTF8 ON
500 Command not allowed by RFC959
CWD /httpdocs
250 CWD command successful
Connect ok!
PWD
257 "/httpdocs" is the current directory
Read directory
TYPE A
200 Type set to A
PASV
425 Will not open data connection - ftp bounce attack
OFFLINE