problems of ftp on NAT load balancer

["wildgoose" <wg4linux@xxxxxxxxxxxxxx>]

I provide http and ftp service with two realserver and two balancer(lvs+ mon +heartbeat).On the balancer ,do NAT .the http works fine,but I cannot connect

the ftp service from the client.The windows ftp client said  connection closed

by remote host.I have insert the ip_vs_ftp module.I think There must be more things

I should to make the ftp service work,but I don't know what is it.