FTP how to?

Hi Guys,

I'm trying to install FTP services with VLM vers 7.0.8.

here is a description :

2 real servers :
ftp1.domain.com (IP1: 192.168.1.X ) and ftp2.domain.com( IP2:192.168.1.Y)
Both are running on debian7 with Proftpd server ( listen port 21 and passiv mode enabled)

FTP virtual service created as follows :
Service NAME :FTP
Alternate Address :non
Service Type: Generic
Activate Service :yes
Force L7:yes
Transparency :yes
No extra ports
Server Initiating protocols : Normal Protocols
Persitence options :nono
Sceduling Method : Fixed weighting (1000 for ftp1 and 500 for ftp2)
idle connection :none
Use address for server NAT : no
Quality of service : Normal service
Real servers : ftp1 and ftp2
VIP: 192.168.2.X

The status is green and up.
FTP is working when connected directly to the real servers. But not working on VIP .

Do I miss something ?
I really appreciate your help,

Thks guys,