jQuery Grid Plugin - jqGrid

I believe there is a bug in the loadBeforeSend method.

If I override this event and set some ID field to pass back to the server, on initial load, the ID that is set does not appear to be passed in the POST request.

IE - I have a simple grid with employees.  One can enter their last name into a text box and click a search button to search for the employee.  No matter what is entered on the first search (page load), all employees are returned.  Clicking the search button a 2nd and subsequent times returns the correct result set.

I viewed the XHR with Firebug and confirmed that a blank value is being passed in the POST method on the first search.

My code is pretty simple.  I simply set the loadBeforeSend property of the grid to call this function:

        $('#gridEmp').appendPostData({
            lastName: $("#TextBox1").val()
        });

Right now, the only way I have found to fix this is to not use the loadBeforeSend override.  I have made a function that instantiates my grid and passes the 'initial' post data to it on through a jQuery ready function.  For subsequent POST data, I use other events (like row select) or handle appending/setting the POST data outside of the grid as in the case of my simple search.

Anyhelp is appreciated.