extJS RadioGroup setValue() function

Question

I have created RadioGroup using the code

var radios = new Ext.form.RadioGroup({
     columns    : 2,
       items: [
             {boxLabel: 'E-Mail', name: 'communication', inputValue: 1},
             {boxLabel: 'Nagios', name: 'communication', inputValue: 2}
        ]
   });

I want to check one of the radio button on some event. How to do it? I tried using:

radios.setValue(true, false);

but it is not working.