Presentation Page with Meta Slider plugin

Theme Nirvana
Site: http://www.arq.ufmg.br/prj/

The plugin Meta Slider is working nice with others plugins, commom pages, widgets, etc.
But not working in the presentation page.

There is this error:
Uncaught TypeError: $(…).flexslider is not a function

I am a begginner and i have know ideia what this means.
Someone can help me please?