need urgent help on f5 ltm Lb traffic.

I have 2 F5 in which, in Lb1 the traffic to port 16789 is ok, but in Lb2. the traffic to 16789 is not showing ok, where as both Lbs are in sync mode.

Lb VIP: 10.243.1.4 port 16789 Internal IP Lb1: 10.243.1.23 Internal Ip Lb2: 10.243.1.24

Server1 IP: 10.243.1.5 Server2 ip: 10.243.1.6

In Lb1 end tcp dump, i check towards VIP (PSH,ACK )

why in Lb2 its sending SYN... Need urgent help