Access to FTP sites when NAT is done with W2K3

Hi,

i do have teh fallowing constelaltion:
(i know that you should not turn a windows box into
a "router" however this has been done ..)

- A server having 2 NIC's an internal and an External
The RRAS service is up and running NAT configured

- Clients can access internet services over NAT (yes this
works ..)
The problem now is that all FTP Sites are not accesible
from clients behing the NAT server, (now i agree you
should not make a WinBox to a Router) on the NAT server
itself no problems ..

Basic Firewall is NOT running (disabled) i know that ftp
opens random ports .. to the client but the client is the
caller so this should work ..

cann anyone tell me what i did miss ?

ohh one last thing if FTP'ing using command line then it
works perfect .. just tah all users are not realyl happy
with the cmd line .. and yes i did block access to this
with GPO's ..

the error i get when accessing ftp sites is:
An Error Occured opening that folder on the FTP server.
Make sure you have persmission to access that folder.
Details:
200 Type Set to A
227 Entering Passive Mode (IP Separetad with comata and
digits 14,16)
426 Connection closed; transfer aborted

please feel free to bomb me and if a usefull hint is
available i would very apreciate this :-)

all of you have fun and enjoy the "Buggy road"
Adi