1.8rc1 Effect: drop not working!

1.8rc1 Effect: drop not working!

The drop effect is not working not even in the demo area! so whats wrong im using jquery 1.4.1 and new ui 1.8rc1!
Any solutions?! or someone with the same problem!

some thing like this:

    
  1. $( "#"+my_current_div ).effect( "drop", { direction: "down" }, "normal", function() {
  2.     /* Do something here . . . */
  3. });