jQuery Grid Plugin - jqGrid

My js:

function onEdit(rowid) {
            debugger;
        }

        function onSuccess(res) {
            debugger;
        }

        function afterSave(rowid, responseText) {
            debugger;
        }

        function onError(res, stat) {
            debugger;
        }

On the Grid's row selected, I call:

$('#FCGrid').editRow(id, false, onEdit, onSuccess, '/Update/Edit/', { mydata: "Drew" }, afterSave, onError);

It will successfully fire the onEdit event, and post to the server.  However, when it posts to the server "mydata" is null.  Additionally, none of the other events declared are ever fired.  Is there something wrong with my code?