How to change CBA button of View classes from your AppUi class?

Hi folks,

I have tried to change CBA button of my View class from AppUi. Application crashes if I do that. But if I change the CBA button from the View class ifself, it works perfectly. Giving the code for changing the CBA button:

//calling this method: UpdataCbaL(R_ORDER_STOP_CBA), R_ORDER_STOP_CBA is declared in RSS file

void UpdateCbaL(TInt aResourceId)
{
    CEikButtonGroupContainer* cba = Cba();
    cba->SetCommandSetL(aResourceId);
    cba->DrawDeferred();
}