if u need only to vailate some button got selected or not on pre print this will works for ur problem.
validate the radio button list on pre print on the radio button group
----- form1.p.RadioButtonList::prePrint - (JavaScript, client) -------------------------------------
if(this.rawValue == "" || this.rawValue == " "){
xfa.event.cancelAction = 1;
xfa.host.messageBox("Please select a value to proceed further.", '1')
}
check the attached file.