Why are Radio buttons different?

This is driving me crazy.

What Parameters should I see when I drag a Radio button component onto the stage ?

I am getting two different types of radio button and I don’t understand why.

One type is a [COLOR=darkred]Movie C[/COLOR][COLOR=darkred]lip[/COLOR] and offers me 6 parameters, including ‘Change Handler’. The other type is not a Movie Clip (this box is greyed out) and offers me 5 parameters, no ‘Change Handler’ parameter, but a ‘Selected’ parameter instead.
They are both instances of [COLOR=darkred]RadioButton.[/COLOR]

[COLOR=black]This is causing my Changehandler AS to return ‘undefined’:[/COLOR]

// Radio buttons 1 - Enquiry or Booking. enquiryType
function radioDisplay1 (component) {
radio1 = component.getValue() ;
}
// Assign function to the group enquiryType
enquiryType.setChangeHandler (“radioDisplay1”) ;

Thank you !