Uncaught TypeError: Cannot read property 'dataTransfer' of undefined

[Valonix]

Hi, i have this error in Chrome.
Can u help me?

[HelloJasonZhang]

I also meet this issue, what is happen on this issue? but the offlical ui demo don't have this issue.

[HelloJasonZhang]

I copy this http://logicbomb.github.io/ng-directives/script/lvl-drag-drop.js code and run it my local enviroment and it is Okey.