If you have a new computer with Windows XP or higher, then E.X. Next Generation won't be available for installation because the compatibility is with Windows 95 and Windows NT. It's possible to install it in Windows XP through Compatibility, but no one will guarantee that. However, if you still have the setup package, right click it and select Properties > Compatibility. Choose Windows NT and start the installation.
If it doesn't work, then you should contact the developer at the following address: http://www.itbroadway.com/contact.html