AJAX对PHP的调用无效

function showEditDialog(regID){
        $.post("getGiftDetail.php", 
                {reg_id: regID },
                function(data) {});

}

I am calling "getGiftDetail.php" with Ajax,, but this php file is not getting called. Please help me! Why isn't this working?

index.html

<script>
    $(function(){
        function showEditDialog(regID){
            $.post("getGiftDetail.php", {reg_id: regID }, function(data) {});
        }
        showEditDialog(5);
    });
</script>

And do not forget to include jquery and use firebug/developers console