Link Load Balancing doesn't work

[massyyyy]

Hi,

to balancing 3 Internet Line, I'am trying to use ZenLoadbalancer in this scenario:

–-------    --------        
                                          |<--->|Router1|<-->|Modem1|<-->InternetLine1
                                          |     ---------    --------
                      ---------------------    ---------    --------        
Client <->|Router4|<--->|Link Load Balancer|<--->|Router2|<-->|Modem2|<-->InternetLine2
                      ---------------------    ---------    --------
                                          |     ---------    --------        
                                          |<--->|Router3|<-->|Modem3|<-->InternetLine3
                                                ---------    --------

All 4 routers are PFSense 2.0.1. If I use PfSense to balancing then I've to active sticky connections, but it doesn't work, so I've tried to configure ZenLoadBalancer both in DATALINK mode and HTTP/TCP mode, and followed a lot of howto but didn't have success if there is PFSense between clients and ZenLoadBalancer.
Is ZenLoadBalancer the best choise or some more suitable tool exists?

... please could someone help me?

Thanks and Regards

Massy