No menu in autocomplete

No menu in autocomplete

I'm not seeing a drop-down when it massage results returned from PHP in my autocomplete text box.

The autocomplete makes the call and returns 'returned' to the success handler, which in turn calls nameListFromProductsArray() and returns a one-dimensional array of products to display.

If you enter 'cr' in the autocomplete field, my success handler returns:
["Crackers","Kraft Dinner, Ritz Crackers"]
but no menu appears.

<code>
    $(function() {
        $("#keyboardtextslave").autocomplete({
            minLength: 2,
            source: function(req,response){
                $.ajax({
                    type: "POST",
                    url: "index.php/auto_products/products_list",
                    data: { fragment: req['term'] },
                    success: function(returned) {
                        response=nameListFromProductsArray(returned); // this does not work
                    }
                });
            },
            select: function(event, ui) {
                alert(ui.item.value);
               // stuff other AJAX data into GUI depending on selection
            }
        });
    });
</code>

Obviously, #keyboardtextslave is not getting response. What am I missing here?

Noah