I update your code to use the store reader's id value instead of the literal 'id'

instead of
Code:
 beforeExpand: function(record, body, rowIndex){
               blah....
                       }else if(this.store && this.tpl && this.lazyRender){
                            blah... blah...
                            this.store.load({params: {id: record.id}});
..i do this...
Code:
 beforeExpand: function(record, body, rowIndex){
               blah....
                       }else if(this.store && this.tpl && this.lazyRender){
                            blah... blah...
                            var params = {};
                            params[this.store.reader.meta.id] = record.id;
                            this.store.load({params: params});
Perhaps there is a cleaner way to get the store's reader and its properties?