I developed a small routine to send and retrieve files via FTP from a virtual disk , based on the classes written by Robert Abram(Thanks!).It works perfectly when I connect via dial-up conection from my office or my clients.
But , one of my clients has ADSL connection to the internet and a firewall based on Linux.When I try to use this routine, it seems to have a sucessful connection but when I try to upload files I receive the following error:

Error 12003
ERROR_INTERNET_EXTENDED_ERROR
EXTENDED ERROR INFO(0) -200 Type set to I
500 Illegal Port Command
500 'LPRT 6,16,0,0,0,0,0,0,0,144,218,99,0,28,0,0,0,2,4,237' Command NOT UNDERSTOOD

This is the same error I receive when I try to connect from Internet Explorer using ftp:\\mylogin@ftp.mydisk.com

I tried some shareware programs and one that works was WS_FTP95 LE when I used a configuration of "Passive Transfers". Do someone knows
what parameters I need to use in the Robert Abram classes to correct the error?

TIA