how to display any custom message in grid panel

I have a requirement.

1. suppose store is not returning data, i want to show some message in the grid panel like 'no records found' message.
2. Another scenario if any exception comes 开发者_JAVA百科from java side i am sending error message to the client, How can i show that message.

Empty text is not working.

Hook into the store's LOAD event:

MyStore.on('load',function() {          
    if (!MyStore.data.length) {
        Ext.Msg.alert('No data found.')
    }
})