[jQuery] Ajax not sending data correctly when it's a variable, but perfect when it the value is typed in instead.

[Namlet]

I have a simple AJAX call:

$.ajax({
            url: "setBMBJSONString.php",
            data: stringJSON.toString(),
<----------------------------------------------------
            success: function(rdata) {
                //var resp = eval('(' + rdata + ')');
                $("body").append(rdata);
            },
            error: function(XMLHttpRequest, textStatus, errorThrown) {
                var e = XMLHttpRequest;
                for (var key in e) {
                    $("body").append(key + ": " + e[key] + "<br />");
                }
            }
        });

That won't work, the data doesn't get to the webservice that way.  But
if I do this instead:

$.ajax({
            url: "setBMBJSONString.php",
            data:
{"prefix":"Bishop","fname":"Nkulu","mname":"Ntanda","lname":"Ntambo","suffix":"Esq.","relation":""},
            success: function(rdata) {
                //var resp = eval('(' + rdata + ')');
                $("body").append(rdata);
            },
            error: function(XMLHttpRequest, textStatus, errorThrown) {
                var e = XMLHttpRequest;
                for (var key in e) {
                    $("body").append(key + ": " + e[key] + "<br />");
                }
            }
        });

Everything works fine!  All I did was print out stringJSON and copy it
and paste it in there.  What's going on?  For obvious reasons I need
to use a variable there.