Passing dropdown box values to variable in WAD

HI

I would like to pass the values from dropdown box to variable in my IP application. These variables are used to restrict the char values in filters of my application. When I change the dropdown box, ,my variable value should automatically change. My dropdown box uses the Char/struc member ( Characteristic_selection) as data binding because I am doing the cascading dropdown boxes for my selection. I can not use variable as data binding for my dropdown box and I know this will work if I use the variable selection as data binding for drop down box.

Thanks

Raj.