How to open port ranges on the Dlink Di-524

I have the Dlink DI-524 router and I need to know how to open up a range of ports for my ftp server and game servers, for example I have opened up
port 16584 for my ftp server, yet I cant figure out how to open the port range which I need to use for passive mode. Under the setup Tab "Virtual
Server" I can open up a single port for a single machine, but cant open up a range of ports and when I go the "applications" tab I can enter a port
range and enable it and just use the trigger port and public ports as the same ones; I have also tried setting the trigger port to 16784 and the
public ports to 15720 - 15820. Does anyone have any ideas?? Thanks