The Mysqli extension is required for this adapter but the extension is not loaded

<?php
class myClass
{
 /**
 about myClass
 */
 
  function myMethod($var1, $var2, $var3... ){
    return $var1.$var2.$var3 ... ;
  }
}
?>

var nc:NetConnection = new NetConnection();
var res:Responder = new Responder(onResult, onFault);
 
nc.connect("http://localhost/amfphp/gateway.php");
nc.call("myClass.myMethod", res, var1, var2, var3, ... );
 
function onFault(responds:Object):void{
 for(var i in responds){
  trace(responds[i]);
 }
}

function onResult(responds:Object):void{
 trace(responds);
}