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?