getJSON call is not going in the call back function

getJSON call is not going in the call back function


Hi All,
I have the this getJSON function:-
                $.getJSON("url",
{onlyShow:selectedPromotion,orderBy:selectedSortType},function(json)
{alert('json data'+json.data);
});
but when i call this function it is able to get the JSON data but when
put any alert in the callback function the alert is not popping up.
Any Idea ?
Thanks for Help