your code looks good, but i am not sure what do you want with the functions.php?
next question, have you user "searchbot" to the correct usergroup added?
this is my list:
$robots = array(
"FAST-WebCrawler" => "searchbot",
"Gulliver" => "searchbot",
"AltaVista" => "searchbot",
"Alexibot" => "searchbot",
"asterias" => "searchbot",
"BackDoorBot" => "searchbot",
"Black.Hole" => "searchbot",
"BlowFish" => "searchbot",
"BotALot" => "searchbot",
"NPBot" => "searchbot",
"Pompos" => "searchbot",
"Scooter" => "searchbot",
"SiteSnagger" => "searchbot",
"Slurp" => "searchbot",
"WebmasterWorldForumBot" => "searchbot",
"zyborg" => "searchbot",
"Google" => "searchbot",
"Googlebot" => "searchbot",
"Googlebot-Image" => "searchbot",
"msnbot" => "searchbot",
"ZACATEK_CZ_BOT" => "searchbot",
"EARTHCOM.info" => "searchbot",
"sherlock" => "searchbot",
"Holmes" => "searchbot",
"ia_archiver" => "searchbot",
"lwp-trivial" => "searchbot",
"appie" => "searchbot",
"Scooter" => "searchbot",
"Gigabot" => "searchbot",
"Wget" => "searchbot",
"jyxobot" => "searchbot",
"Xenu Link Sleuth" => "searchbot",
"SeznamBot" => "searchbot",
"ia_archiver" => "searchbot",
"Yahoo! Slurp" => "searchbot",
"Yahoo" => "searchbot",
"help\.yahoo\.com" => "searchbot",
);