Will, Thanks For replying.
Here are details you asked for :
No, there is no javascript error in console.
Wp Version : Version 3.8
ACF : Version 4.3.4
Browser : Mozilla
some times it allows me to rearrange fields very first time(Not everytime) when I open site admin panel to manage fields. after that not at all allowing me any editing. however I am able to add new fields.