If I understand your layout correctly you have successfully setup nat and policy from internet sources to your public ip address nat to an internal server. But access to the same public ip address to those servers from internal addresses does not work.
For the internal traffic to work you need two policies nat and security.
For the nat policy you likely can simply add the internal zone or zones as the source zone to the working nat policy from the internet zone to the servers.
For the security policy you need to confirm there is and existing security policy or create a new one from the source zone of the clients to the destination zone of the internal address after nat of the servers covering icmp, http and any other desired protocols.
------------------------------
Steve Puluka BSEET - Juniper Ambassador
IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP - Retired)
http://puluka.com/home------------------------------