How to fix Firebug Error

[Nirjonadda]

I have one error show on the Firebug , How to fix on this error ?

TypeError: $(...).lightBox is not a function
	

$(".portfolio_holder a[rel^='group1'], .portfolio_holder2 a[rel^='group1']").lig...

	//lightbox
	//--------
	$(".portfolio_holder a[rel^='group1'], .portfolio_holder2 a[rel^='group1']").lightBox();
}) // end document.ready call

 

[Ozzy47]

Is the lightbox part of a mod?