Add child to State
<?xml version="1.0" encoding="utf-8"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"> <mx:states> <mx:State name="Charge"> <mx:AddChild relativeTo="{form1}" position="lastChild"> <mx:FormItem label="Charge Number" id="formitem1"> <mx:TextInput/> </mx:FormItem> </mx:AddChild> </mx:State> <mx:State name="Check"> <mx:AddChild relativeTo="{form1}" position="lastChild"> <mx:FormItem label="Routing Number" id="formitema"> <mx:TextInput/> </mx:FormItem> </mx:AddChild> </mx:State> </mx:states> <mx:transitions> <mx:Transition id="paymentTransitionCharge" fromState="*" toState="Charge"> <mx:Parallel targets="{[formitem1,formitema]}"> <mx:Fade duration="400"/> <mx:Move xFrom="0" yFrom="0" duration="400"/> </mx:Parallel> </mx:Transition> <mx:Transition id="paymentTransitionCheck" fromState="*" toState="Check"> <mx:Parallel targets="{[formitema,formitem1]}"> <mx:Fade duration="400"/> <mx:Move xFrom="0" yFrom="0" duration="400"/> </mx:Parallel> </mx:Transition> </mx:transitions> <mx:Form x="103" y="56" width="397" height="284" id="form1"> <mx:RadioButtonGroup id="radiogroup1"/> <mx:RadioButton x="143" y="70" label="Check" groupName="radiogroup1" click="currentState='Check'"/> <mx:RadioButton x="143" y="94" label="Charge" groupName="radiogroup1" click="currentState='Charge'"/> </mx:Form> </mx:Application>