problem getting $_REQUEST vars in page

Hi,

Developing my first plugin, I have run into some problems. My plugin is displayed on a standard page. On this page, I have an index with links for every letter in the alphabet. When the user clicks a link, I want to display all records from the database that has a name that starts with the selected letter. However, I can’t catch the GET vars. My links look like this:

<a href="?action=index&ltr=A">A</a>

The function where I handle the links looks like this:

if ( isset( $_REQUEST['action'] ) ) {
  switch( $_REQUEST['action'] ) {
	case 'search' :
	  $output .= do_search();
	  break;
	case 'index' :
	  $output .= show_index();
	  break;
  }
}

The search action works fine when I submit the search form (action=post), but the show_index() function does not get called when i click on the link above.

I’m fairly new with both php and wordpress, so I’m probably just doing something wrong, but I can’t figure out what.

Any suggestions will be appreceated.

/Rasmus