jQuery Grid Plugin - jqGrid

I have an ajax panel which when opened creates a grid on the right side of the screen containing a jqgrid. I can add rows to the grid but when I close thepanel and reopen it I get a recursion error when trying to add another row. The action of adding a row occurs by clicking on the + icon at the bottom of the grid. Included below is the code. The Error i get is Uncaught RangeError: Maximum call stack size exceeded. I do know that this function gets called repetitively after the panel is opened again and the + icon is clicked.
Anyone know what the issue may be?

 oldAddRowData = $.fn.jqGrid.addRowData;
 addRowData: function (rowid, rdata, pos, src) {    $.jgrid.extend({
 addmode = true;            fromadd = true;
 SwitchGridHighlightOff('#NewProductGrid');
 $('.navtable').find('.ui-icon-pencil').css('display', 'none');
 Verb: 'i' };
 rdata = { ProductGroupId: strproductgroupid, ProductCode: '', Description: '', BoxQuantity: '1', Company: companycode, 

 return oldAddRowData.call(this, rowid, rdata, pos, src);

}   

});