Web Client installation

Hello All,

I have small problem with installation of Web Client in NAV 2013, i have two different version is available in Server one is NAV 4.0SP3 and other is NAV 2013,

and there are 3 different database in NAV 2013 , now when i try to install the web client its installing the demo database and its not allowing me to change the database instance and the sql instance, by default its taking NAV 4.0Sp3 server name,

can any idea how to install the web client.

thanks in advance