dropdownlist in updatepanel1 to update updatepanel2

I have 2 ddl in an updatepanel1 and when one is selected, panel refreshes to load ddl #2 based on ddl1 choice. Works great, love it. Now can ddl2 change cause updatepanel2 to refresh?doh! nevermind... set update to conditional and call updatepanel.update from codebehind.