How to access a public Ip address from a box inside security group

I have a box on amazon ec2 which has a elastic ip assigned to it. I have a security group s1 for this box. I have another security group s2 which has a box which need to access port on the public ip address. I have added a rule to s1 security group saying allow port access from s2 security group.

Even though with the above configuration I was not able to access the public ip address port from a box which has security group as s2.

Please let me know how can I solve this