Unfortunately, they changed the pinout of that connector between the SE/SE30, and the Classic / Classic II. The only functional difference is that sound in the Classics goes through the main connector instead of its own lead, but they changed everything else as well.

I seem to keep referring you to existing threads, I guess that shows the tremendous value this forum represents! Have a look here, the last post in this thread sums it up: http://68kmla.org/forums/viewtopic.php?f=7&t=22306#p217909