The template author decided to suppress the quicksearch sidebar plugin. I think it would have been better to offer a template option to hide/not hide.

Using a text editor, open the file sidebar.tpl. Within that file, you will find this code:
{if $item.class == "serendipity_quicksearch_plugin ...

I just installed the Sagittarius A template and am having a problem with the search field.

It's a great theme (well done!) but for some reason the quicksearch plugin doesn't display on the page. The plug in is active. I can configure it and move it around in the administration but it doesn't ...