jQuery.getJSON calback function problem

jQuery.getJSON calback function problem

hi,

I'm using jquery for making a jsonp call for obtaining cross-domain data. The response is coming and I have verified the same from the net panel of the firebug add-on of Mozilla browser. The problem that I am facing is I'm not able to access the response obtained in the callback function. Also, I'mnot being shown any error message for this. The following is the code snippet I have added in the head tag of the html page and I am invoking this makeCall() function on the onload event of the body tag -

function makeCall(){
        alert("makeCall");
        jQuery.getJSON("<requestURL>?jsoncallback=?",
            function(data) {
            alert("data: "+data);

            });
    }

<BODY onload="javascript:makeCall();">

What is the mistake I'm making or am I missing something? What are the changes I need to make in this code?

Thanks in advance,
meamitava.