This is my very first wix project. I downloaded wix 3.6 rc.
My installation project includes 2 wcf and 1 silverlight projects. Everything works fine with default Wix UI. But now
Finally I found an eye opener article on wix here How to add custom UI
After a long struggle to understand how wix works, the above link to codeproject helped me understand. Especially the part that explains creating UI (MyWebUI.wxs in that article) was the life saver.