why Nepal is not able to implement the federal system?

I have no idea. Read lots and see if you can get any ideas:

http://www.bing.com/search?q=government+reform+in+nepal&form=EDGNTC&qs=PF&cvid=2f532c03951e40108cbf28cef2060d70&pq=government%20reform%20in%20nepal