Jquery Loading Problem

Jquery Loading Problem.If i lclick on what we do that div should scroll at the same time scroll bar should display.
Link:[url]http://82.80.196.84/~genesisa[/url]
I am getting the error like below:
Cannot read property ‘top’ of null jquery.mCustomScrollbar.js near;
if($dragger.position().top>$dragger container.height()-$dragger.height())

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