Sencha Touch error: 'myapp.mainpanel has no method setActiveItem'

Edit: Upon further examination I discovered that I hadn't included certain namespaces. Adding the relevant name spaces now gives the error: 'myapp.mainpanel has no method setActiveItem'

I am trying to build a sencha touch web app using the card layout mechanism. I make use of the following handler on a button on the landing page:

handler:function(){
            myapp.mainpanel.setActiveItem(myapp.cards.vehicleSearchResults, { type: 'slide', cover: false, direction: 'left'})
            }

But when I click on the button I get the error: Sencha Touch error: 'myapp.mainpanel has no method setActiveItem'

Does this mean myapp.cards.vehicleSearchResults is undefined?

I define it here:

myapp.cards.vehicleSearchResu开发者_如何学Golts = new Ext.Panel({
    scroll:false,
    layout:{
            type:"vbox",
            align:"stretch"
    },
    id: "vehicle-search-results-card",
    dockedItems: [myapp.toolbars.searchResultsTitle, myapp.toolbars.searchResultsNav, myapp.toolbars.searchResultsCaption]

})

Any clues as to what I am doing wrong based on the above code?

The setActiveItem() method is only available if the panel has a card layout. Make sure you add the 'card' layout property in your panel definition.