Problem with managing two IP

[MscEliot]

I have 2 IP on my VPS which has a DA cp, One of them is marked as Server (IP1) and the other one is used as Share (IP2)...

These is just one site (user) on IP2. Every thing of this website (DNS names) is set to IP2 and the website operates perfectly...
In this website there is a script tries to connect to a web service that checks the IP of clients to give service. But this Web Service gets IP1 as my external IP while everything is set to IP2 in this website..!! Do you this there is some problems in my settings?!
Or in other words, How can I change my external IP to IP2 in this website

 

[zEitEr]

Use CURL in PHP script

CURLOPT_INTERFACE                 The name of the outgoing network interface to use. This can be an interface name, an IP address or a host name.

http://php.net/manual/en/function.curl-setopt.php

Or try to use iptables with checking UID.