Ext Js How to Pass Params to Server Code

I've got two Ext GridPanels and want to pass an OrderID value from my Orders store to my PHP server code As I look through the docs, I see params, baseparams and beforeload listeners as possible ways to achieve this. The code below seemed straight forward but my param doesn't seem to get passed.

    OrdersGrid.on('rowclick', function(grid, rowIndex, e) {
    var selectedRecord = this.getSelectio开发者_StackOverflow社区nModel().getSelected();
    var val = selectedRecord.get('OrderID');
    ItemsDataStore.load( {params : {OrderID: val }});
    });

Any ideas on how to debug this appreciated. Thanks.

---

Set the baseParams on the store:

ItemsDataStore.baseParams.OrderID = val;
ItemsDataStore.load();