IPTables Port Mapping / Forwaring

I'm not that good at IPTables so bare with me. I think I got the rules correct though but it doesn't work Here is what I am trying to do.

I have a server at let's say 111.222.11.10(I will call this server A) and another at 111.222.11.20(I will call this server B).

These servers are in same datacenter.

What I am trying to do here is when a user accesses port 2000 on server A, I want server A to forward/proxy the port to 2000 at Server B. I have tried the following so far.
Non of them worked.

iptables -t nat -I PREROUTING -p tcp --dport 2000 -j DNAT --to 111.222.11.20:2000
iptables -I FORWARD -p tcp -d 111.222.11.20 --dport 2000 -j ACCEPT

[root@n1-cluster ~]# iptables -t nat -I PREROUTING -p tcp --dport 2000 -j DNAT --to 111.222.10.20:2000
[root@n1-cluster ~]# iptables -t nat -A PREROUTING -p udp --dport 2000 -i eth0 -j DNAT --to 111.222.10.20:2000

iptables -A FORWARD -i eth0 -p tcp --dport 2000 -j ACCEPT
iptables -t nat -A PREROUTING -p tcp -i eth0 --dport 2000 -j DNAT --to-destination 111.222.10.20:2000
Yes, I have done service iptables save and start.
Also iptables -F

Any ideas on what may be wrong?