<com:TContent ID="Content">

 <com:TRequiredFieldValidator
    ControlToValidate="rad_button_list"
    Text="You must click one"
    Display="Dynamic"
    ValidationGroup="Group"
    />
  <br />
  <com:TActiveRadioButtonList
    ID="rad_button_list"
    OnCallback="radChange">
    <com:TListItem Value="yes" Text="Yes" />
    <com:TListItem Value="no" Text="No" />
    <com:TListItem Value="whynot" Text="Why not?" />
  </com:TActiveRadioButtonList>
  <br />
  <com:TActiveLabel
    ID="label"
    Text="Choice : "  />
  <br /><br /><br />
  <com:TActiveButton
    ID="action_button"
    Text="action"
    OnCallback="action"
    ValidationGroup="Group"  />


</com:TContent>