hoverclass not changing

i am playing with draggable elements for the first time in my rails
app. i got everything working right except for changing the class of
the element when an item hovers over it.

<%= drop_receiving_element('drop',
               :accept => 'movable-job',
               :hoverclass => 'hover',
               :loading => visual_effect(:fade),
               :url => { :action => 'move_job' }) %>

that's what i have, but the appearance doesn't change on the drop
element.

is there something i did wrong?