What steps will reproduce the problem?
1. create an application
2. add an advanced form inside an addChild step
3. call resetForm

What is the expected output? What do you see instead?
the form should be reseted instead I got the following output :
TypeError: Error #1009: Cannot access a property or method of a null object
reference.
	at flexlib2.containers::AdvancedForm/::resetValues()
	at flexlib2.containers::AdvancedForm/resetForm()
	at eatProject.view.login::LoginPanel/reset()
	at eatProject.view.login::LoginPanel/___SetEventHandler2_handler()

In fact It seems that when placed between states  marker the  
modelStack[ snapshotKey ] isn't set

What version of the product are you using? On what operating system?
flex 2.01
flexlib 1.6
windows XP SP2
Please provide any additional information below.