As Question and Answer related to ng-disabled didn't help, so I am writing this question for help.
The problem is in my angularjs app ng-disabled is not working properly.
Here is the jsfiddle of the problem
http://fiddle.jshell.net/80cLw91j/
the desired behaviour is when you click the start button, all input elements including the start button should get disabled and stop button should get enabled and vice versa when you click stop button.