Getting an error while using Exporter

[harjits]

I'm using the exporter functionality to export data from a grid to Excel. When my grid is loaded the 3rd time, I see this error

Ext.Button.Ext.extend.onDisableChange[/COLOR]ext-all-debug.js:31696Ext.Button.Ext.extend.onEnable[/COLOR]ext-all-debug.js:31688

• • • Ext.extend.enable[/COLOR]ext-all-debug.js:11711
    • setLink[/COLOR]:9090/sentry-web/static/js/sentry/Exporter-all.js:159
    • EXTUTIL.Event.fire[/COLOR]ext-all-debug.js:310
    • ]EXTUTIL.Observable.fireEvent[/COLOR]ext-all-debug.js:54
    • Ext.data.Store.Ext.extend.loadRecords[/COLOR]ext-all-debug.js:24557
    • [COLOR=red !important]Ext.extend.onRead[/COLOR]ext-all-debug.js:25780
    • (anonymous function)[/COLOR]ext-all-debug.js:25744
    • Ext.extend.handleResponse[/COLOR]ext-all-debug.js:4646
    • handleTransactionResponse[/COLOR]ext-base-debug.js:1887
    • checkResponseext-base-debug.js:1935
    • (anonymous function)ext-base-debug.js:922
• 
  
  
  My code is as follows
  
  
  

   if (parent.phoneGrid.store.getTotalCount() > 0) {
                          var exportButton = new Ext.ux.Exporter.Button({
                              component:parent.phoneGrid.gridPanel,
                              text:"Export to .xls"    });
                          parent.phoneGrid.gridPanel.getTopToolbar().add(exportButton);
                          parent.phoneGrid.gridPanel.getTopToolbar().doLayout()
                      }

  [/COLOR]