LiveChange not working in ValueHelp field

Hi All,

Am trying to use setValueState("None") on the VH field while mandatory validation. I am using Livechange function, but valuestate None is not working as i am not typing any key physically i get the value from VH dialog. So "LiveChange" is not working here. So can anyone help me to where how can i set the ValueState property depending on the values entered in VH field.