[jQuery] tablesorter options not working

Hi all. I've the following code:

  jQuery('#bid_requests_for_part').tablesorter({
    sortColumn: 'Vendor',
    sortClassAsc: 'headerSortUp',
    sortClassDesc: 'headerSortDown',
    headerClass: 'header',
    stripingRowClass: [ 'even', 'odd' ],
    stripeRowsOnStartup: true
  });

The sorting portion works, but none of the options are taking effect.
Except headerClass -- that is setting the class of the <th> elements.
Beyond that, nothing; no striping, no table header styles.

I've included the <thead> and <tbody> elements in my table, too.

Any ideas?