I tried both rules, either NAT or  FWD_Fast, neither of them works.
I enabled logging for this rules, and here is a copy of the log messages, maybe they mean more to  you than to me. 
2010-01-12
06:57:45    Info    CONN
600001    ldap    TCP    lan
lan    192.168.30.25
190.136.44.74    2828
389    conn_open
satdestrule=ldap conn=open 
2010-01-12
06:58:46    Info    CONN
600002    ldap    TCP    lan
lan    192.168.30.25
190.136.44.74    2828
389    conn_close
close
conn=close origsent=144 termsent=0 
I have exactly the same problem when I try to access our web server, if I point it to our local address, it works fine, but if I point it to the Internet address, it does not work. Maybe it is easier to solve the http problem first, though I guess it´s the same problem everywhere.
Thanks for your help.
José